First, then, we have the great forest-covered swamps, like those which

now occupy the valley and delta of the Mississippi. They are composed

in many cases of pure vegetable matter without any intermixture of

earthy sediment. A dense growth of reeds, and shrubs, and herbage of

every kind, covers the whole surface of the land, mixed up with the

decaying leaves and prostrate trunks of forest-trees. Sir Charles Lyell

mentions a very remarkable fact observed in the swamps of Louisiana.

During an unusually hot season, when any part of a swamp is dried up,

if the surface be set on fire, a pit is burned into the ground many

feet deep, in fact, as far down as the fire can descend without meeting

water; and it is then found that scarcely any residuum or earthy matter

is left.[62]

Vegetable strata of this kind are produced, not only upon dry land by

the growth and decay of forests, but also beneath the waters of lakes

and estuaries, by the accumulation of Drift-timber borne along in the

current of swollen rivers. The Mackenzie River, which drains a great

part of Northwestern America, affords many admirable illustrations.

Flowing as it does from south to north, it is subject to annual

inundations when the snows begin to melt in the higher parts of its

course, while the channel lower down, situated in colder latitudes, is

still blocked up with ice. At this season then it overflows its banks,

and sweeping through vast forests, carries away thousands of uprooted

trees in its impetuous torrent.

“As the trees,” says Dr. Richardson, “retain their roots, which are

often loaded with earth and stones, they readily sink, especially

when water-soaked; and accumulating in the eddies, form shoals, which

ultimately augment into islands. A thicket of small willows covers

the new-formed island as soon as it appears above water, and their

fibrous roots serve to bind the whole firmly together. Sections of

these islands are annually made by the river; and it is interesting to

study the diversities of appearances they present according to their

different ages. The trunks of the trees gradually decay until they

are converted into a blackish-brown substance resembling peat, but

still retaining more or less of the fibrous structure of the wood; and

layers of this often alternate with layers of clay and sand, the whole

being penetrated, to a depth of four or five yards or more, by the

long fibrous roots of the willows. A deposition of this kind, with the

aid of a little infiltration of bituminous matter, would produce an

excellent imitation of Coal, with vegetable impressions of the willow

roots.

“It was in the rivers only that we could observe sections of these

deposits; but the same operation goes on, on a much more magnificent

scale, in the lakes. A shoal of many miles in extent is formed on the

south side of Athabasca Lake by the Drift-timber and vegetable débris

brought down by the Elk River; and the Slave Lake itself must in

process of time be filled up by the matters daily conveyed into it from

Slave River. Vast quantities of Drift-timber are buried under the sand

at the mouth of the river, and enormous piles of it are accumulated on

the shores of every part of the lake.”

Not unfrequently it happens that these strata of vegetable matter, with

the roots and trunks of trees, their branches, fruits, and leaves, more

or less perfectly preserved, are covered over by subsequent deposits.

Such accumulations, we are assured by Doctor Mantell, have been found

deep in the soil on the coast of England, in places that are still

subject to periodical inundations. “The trees are chiefly of the oak,

hazel, fir, birch, yew, willow, and ash; in short, almost every kind

that is indigenous to this island occasionally occurs. The trunks and

branches are dyed throughout of a deep ebony color by iron; and the

wood is firm and heavy, and occasionally fit for domestic use; in

Yorkshire and elsewhere, timber of this kind is sometimes employed in

the construction of houses.”[63] Here, then, is the first stage of

the conversion of wood into Coal,--a stratum more or less compacted

together of vegetable matter, spread out sometimes over the surface of

the dry land, sometimes on the floor of lakes and estuaries, and often

buried beneath an accumulation of subsequent deposits.

The next stage in the process of transformation may be represented by

those Peat Bogs which constitute one of the most remarkable physical

characteristics of Ireland, covering as they do an area equal to

one-tenth of the whole island. In these the vegetable matter is more

closely condensed, but the structure of the plants from which the

Peat is derived is still preserved, and may be distinctly recognized

by the naked eye. Nay, we have still the prostrate trunks of trees

lying around on every side as they fell to the ground in their ancient

forests. The researches recently pursued upon this subject have brought

to light a fact which is very much to our present purpose; for it

seems to prove our thesis by direct evidence. “In Limerick, in the

district of Maine, one of the States of North America, there are Peat

Bogs of considerable extent, in which a substance exactly similar to

_cannel coal_ is found at the depth of three or four feet from the

surface amidst the remains of rotten logs of wood and _beaver sticks_:

the peat is twenty feet thick, and rests upon white sand. This coal

was discovered on digging a ditch to drain a portion of the bog, for

the purpose of obtaining peat for manure. The substance is a true

bituminous coal, containing more bitumen than is found in any other

variety. Polished sections of the compact masses exhibit the peculiar

structure of coniferous trees, and prove that the coal was derived from

a species allied to the American Fir.”[64] A similar phenomenon was

observed by Doctor Dieffenbach in the Chathain Islands. In the same

bed of peat he was able distinctly to trace a gradual transition from

pure vegetable matter to a mineral substantially identical with common

coal.[65]

But though Peat may thus, as it should seem, pass directly into pure

Coal, there are many cases in which it first assumes a more imperfect

form, known under the name of Lignite. This substance is described

as of a brownish color, “soft and mellow in consistence when freshly

quarried, but becoming brittle by exposure, the fracture following

the direction of the fibre of the wood.”[66] It clearly occupies an

intermediate position between Peat and Coal. Like the former, it still

exhibits the stems and woody fibre of the plants from which it is

derived, very little altered in their structure; while on the other

hand it is already beginning to acquire some of the consistency and

density of Coal; to which also it approaches much more closely in its

chemical composition. It should be remembered, moreover, that Lignite

does not designate a substance of a fixed, invariable character. On the

contrary, under the one general name are comprised a definite number of

varieties, leading from one extreme to the other by a series of almost

insensible gradations; the extreme variety on one side being scarcely

distinguishable from Peat, while the extreme variety on the other is

practically identical with ordinary Coal. It can hardly be doubted,

therefore, that Coal must have the same origin as Lignite, while it is

at least equally certain that Lignite has been derived from Peat; and

we have already seen what overwhelming evidence may be adduced to show

that the origin of Peat is to be sought for in the sunken swamps and

forests of a long past age.

Lastly, when we come to examine the texture of Coal itself, we find

much to confirm the conclusion at which we have thus arrived. In beds

of pure Coal the remains of many species of plants have been detected,

and sometimes in such abundance as to constitute visibly the bulk of

the Coal. Even large trees are sometimes found standing erect in the

Coal fields, with their bark actually converted into this mineral. The

annexed Figure represents a portion of the stem, together with the

roots of a tall forest tree, Sigillaria, discovered not long ago in a

Coal mine at Saint Helens, near Liverpool. The stem, which was nine

feet high, was found erect in the seam of Coal, while the roots, ten

in number, stretched away into the vegetable soil beneath.

[Illustration: Fig. 11.--Stem and roots of a Forest Tree, Sigillaria.

From a Coal-mine, near Liverpool.

_a_, The trunk traversing a bed of Coal.

_b_, The roots spreading out in the underclay.]

Not less than thirty such trees, some of them four or five feet in

diameter, and all incrusted with Coal, were laid bare a short time

since, in a Colliery near Newcastle, within an area of fifty yards

square. “In 1830,” writes Sir Charles Lyell, “a slanting trunk was

exposed in Craigleith quarry, near Edinburgh, the total length of which

exceeded sixty feet. Its diameter at the top was about seven inches,

and near the base, it measured five feet in its greater, and two feet

in its lesser, width. The bark was converted into a thin coating of

the purest and finest Coal.” Again, “in South Staffordshire, a seam of

Coal was laid bare in the year 1844, in what is called an open work

at Parkfield Colliery, near Wolverhampton. In the space of about a

quarter of an acre, the stumps of no less than seventy-three trees,

with their roots attached, appeared, some of them more than eight feet

in circumference. The trunks, broken off close to the root, were lying

prostrate in every direction, often crossing each other. One of them

measured fifteen, another thirty feet in length, and others less. They

were invariably flattened to the thickness of one or two inches, and

converted into Coal. Their roots formed part of a stratum of Coal ten

inches thick, which rested on a layer of clay two inches thick, below

which was a second forest resting on a two-foot seam of Coal. Five feet

below this again was a third forest, with large stumps of Lepidodendra,

Calamites, and other trees.”[67]

* * * * *

We have now brought to a close a very important line of argument in

the Science of Geology. We have pointed out that, in the strata which

compose the Crust of the Earth, there are rocks of various kinds,

distinguished from one another as well by the nature of the materials

which compose them, as by the manner in which these materials are

arranged together; and we have shown that rocks presenting the same

general appearances, and composed of exactly the same materials, are

being produced in the present age upon the Surface of the Earth,

through the agency of natural causes. Moreover, we have closely

examined, in certain cases, the nature of the process by which the

formation of these rocks is accomplished at the present day; and we

have seen how difficult it is, when the facts of the case are once

clearly before us, to resist the conclusion that the rocks which we now

find buried in the Earth, were produced in some former age, by the same

causes which are still at work. We shall next proceed to inquire how

far this conclusion is confirmed by the independent evidence of Fossil

Remains.

But before entering on a new line of argument, it is fit we should

take notice of an objection which has sometimes been urged against the

reasoning we have hitherto pursued, and which has done much to create

and to keep alive a prejudice unfavorable to the Science of Geology.

Religious writers have not unfrequently insinuated, and sometimes have

plainly asserted, that, in ascribing the present structure of the

Earth’s Crust to the operation of natural causes, Geologists would

seem to make no account of God’s Omnipotence. A moment’s reflection

will convince the reader that this charge is utterly unphilosophical.

Is it not plain that the more fully we appreciate and acknowledge the

wonderful works of Nature, the more deeply must we become impressed

with the power and wisdom of Him who is the Author and Ruler of Nature?

To say that secondary causes exist, and to point out the monuments that

bear witness to their operation in long passed ages, is not to deny,

but rather to affirm the existence of a Great First Cause, upon whom

they all depend for their existence, their preservation, and their

guidance.

We are everywhere reminded by abundant evidence, that it has pleased

the Great Creator to employ the agency of His creatures in the

fashioning and the adorning of this material universe. He does not

create at once, as He well might do, the great oak of the forest; but

He allows the seed to sink into the earth, where it is watered by the

gentle dews of Heaven, and fructified by the genial warmth of the sun;

soon it puts forth a tender germ; the germ, in time, imbibing the

elements of its support from the air and the earth, becomes a sappling,

and the sappling a tree, which spreads its huge branches on every side,

and serves for many purposes of ornament and of use. Or let us take

the case of the honeycomb, that most curious and ingenious work, at

once the palace and the storehouse of a vast and busy community. It is

not produced in a moment by a simple act of creation. God has not made

it Himself, but He has taught the bee to make it. In like manner He

has provided for the little birds, not by building their nests, but by

infusing into their nature that mysterious instinct which prompts them

to build, and guides them in their work.

Geologists, therefore, when they undertake to explain the existence

of Stratified Rocks, not by the immediate action of the Creator, but

by the intervention of natural causes, are not on that account to be

accused of impiety. They do not disparage, but rather magnify His

glory, when they expatiate upon the endless variety of agents which,

according to their theory, He has employed in the structure of the

material world. If the honeycomb, as a work of contrivance and design,

excites the wonder and admiration of the philosopher, what must we

think of the contrivance and design exhibited by Him who has made, not

the honeycomb only, but the bee that builds the honeycomb? And so, too,

we get novel and unexpected views of God’s Omnipotence, when, through

the science of Geology, we come to understand the vast and harmonious

series of secondary causes by which he has brought the Crust of the

Earth into its present form and shape. The impress of His hand is

stamped upon His works; and all that is wonderful and attractive in

Nature is but the token of His power and the shadow of His beauty. And

so our national poet has sung:

“Thou art, O GOD, the life and light

Of all this wondrous world we see;

Its glow by day, its smile by night,

Are but reflections caught from Thee.

Where’er we turn, Thy glories shine,

And all things fair and bright are Thine.”

[Illustration]

_CHAPTER X._

FOSSIL REMAINS--THE MUSEUM.

_Recapitulation--Scope of our argument--Theory of

stratified rocks the framework of geological science--The

theory brings geology into contact with revelation--the

line of reasoning hitherto pursued confirmed by the

testimony of fossil remains--Meaning of the word

fossil--Inexhaustible abundance of fossils--Various states

of preservation--Petrifaction--Experiments of Professor

Göppert--Organic rocks afford some insight into the fossil

world--The reality and significance of fossil remains must

be learned from observation--The British Museum--Colossal

skeletons--Bones and shells of animals--Fossil plants and

trees._

Reader, you are beginning to suspect us. ‘How long do we propose to

detain people?’ For anything that appears we may be designing to write

on to the twentieth century. ‘And _whither_ are we going?’ Toward what

object? which is as urgent a quære as, _how far_? Perhaps we may be

leading you into treason. You feel symptoms of doubt and restiveness;

and like Hamlet with his father’s ghost, “you will follow us no further

unless we explain what it is that we are in quest of.”

These words of Thomas De Quincey to his readers, in the middle of one

of his discursive essays, which, interesting as they certainly are in

all their parts, yet sometimes beget a feeling of weariness from the

uncomfortable apprehension that they will not come to an end, are,

perhaps, scarcely less appropriate in our own case. It may be that our

readers have been left too long in the uneasy state of suspense and

hope deferred. They came to our pages to look for a practical solution

of the question, Is Geology at variance with the Bible? And what avails

it, they may ask, to discourse to them of the Gulf Stream, and Rivers,

and Glaciers, and Alluvial Plains, and Coral Rocks, and Coal Mines?

With painful steps they have been toiling after us through tedious

disquisitions, straining their eyes to see the end, but the end is not

yet in sight. Well, then, if they will rest for a few minutes by the

way, we will pause, too, and tell them what we are about, and try to

bring out more clearly the object at which we are aiming.

Our design from the beginning was to consider the points of contact

between Geology and Revelation; to examine the relations that exist

between these two departments of knowledge,--one resting upon reason

and observation, the other given to us from Heaven; and to inquire

how far it may be possible to adopt the conclusions of the former,

while we adhere, at the same time, with unswerving fidelity, to the

unchangeable truths of the latter. With this end in view, we proceeded

at once to sketch out the more prominent features of Geological theory;

not the particular theory of one writer, or of one school, but that

more general theory which is adopted by all writers, and prevails in

every school. This theory, we were all well aware, is in many points

widely at variance with the common notions of sensible and even

well-informed men who have not devoted much attention to the study of

Physical Science. And it occurred to us that, possibly, many of our

readers might be disposed to cut the controversy short by rejecting,

in a summary way, the whole system of Geology, and treating it as an

empty shadow or an idle dream. This, we were convinced, would be a

mistaken and mischievous course. Geology is not a house of cards that

it may be blown down by a breath. It is a hypothesis, a theory, if you

will; but no one can in fairness deny that behind this theory there are

facts,--unexpected, startling, significant facts; that these facts,

when considered in their relation to one another, when illustrated

by the present phenomena of Nature, and skilfully grouped together,

as they have been by able men, disclose certain general truths, and

suggest certain arguments, which do seem to point in the direction of

those conclusions at which Geologists have arrived.

It follows that he who would investigate fairly the claims of Geology,

must first learn to appreciate the significance of these facts, and

to estimate the value of these arguments. And this is precisely what

we have been trying to do. We are not writing a treatise on Geology.

Certainly not: it would be presumptuous in us, with our scanty

knowledge, to attempt it. Besides, Geology has it own professors, and

its lecture-halls, and its manuals. Neither do we mean to assume the

character of the advocates or champions of Geology. It does not ask

our services; in its cause are enrolled no small proportion of the

most illustrious names which for the last fifty years have adorned the

annals of Physical Science. Nor do we want even to enforce upon our

readers that more general theory of Geology which we are endeavoring to

explain and illustrate. Our purpose is merely to collect from various

sources, and to string together, the evidence that may be adduced in

its favor; that so, when we come hereafter to consider this theory

in its relation with the History of the Bible, we may not incur the

risk of discomfiture by denying that which has been proved by facts,

but rather approach the subject with such knowledge as may help us to

discover the real harmony that we know to exist between the truths

inscribed on the works of God, and those which are recorded in His

Written Word.

In the accomplishment of this task we have devoted ourselves chiefly to

the study of the Aqueous or Stratified Rocks. According to Geologists,

these rocks, such as we find them now, were not the immediate work of

creation, but were slowly produced in the long lapse of ages, and laid

out one above another, by a vast and complex machinery of secondary

causes. The elements of which they are composed were gathered together

from many and various sources; from the ocean, from the air, from other

pre-existing rocks; and, for aught we know, may have had a long and

eventful history before they came to assume their present structure

and arrangement. Thus, for example, the Conglomerates, and Sandstones,

with which we are so familiar, are made up of broken fragments derived

from earlier rocks, and then transported to distant sites by the

mountain torrents, or the stately rivers of vast continents, or the

silent currents of the sea; the Limestone with which we build our

houses is the work of living animals that once swarmed in countless

myriads beneath the waters of the ocean; and the Coal which supplies

the motive power to our manufactories, our railways, our ships of war

and commerce, is but the modern representative of ancient swamps and

forests, which, having been buried in the earth, and there, by the

action of chemical laws, endowed with new properties, were laid by for

the future use of man in the great storehouse of Nature.

This mode of accounting for the origin and formation of Stratified

Rocks constitutes in a manner the framework that supports and binds

together the whole system of Geology. If it be once fairly established,

Geology is entitled to take high rank as a Physical Science. If on

the contrary it should prove to be without foundation, then Geology

is no longer a science, but a dream. Moreover, it is this theory of

stratification which, from the first, has brought Geology into contact

with Revelation. For Geologists have been led to infer the extreme

Antiquity of the Earth, from the immense thickness of the Stratified

Rocks on the one hand, and, on the other, the very slow and gradual

process by which each stratum in the series has been, in its turn,

spread out and consolidated. Those likewise who claim for the Human

Race a greater Antiquity than the Bible allows, seek for their proofs

in the supposed origin and antiquity of those superficial deposits, in

which the remains of Man or of his works are sometimes found entombed.

It is not to be wondered at, therefore, that the theory of Stratified

Rocks should engage the largest share of our attention when we

undertake to discuss the relation in which Geology stands to Revealed

Religion. For the present we say nothing about the conclusions that

flow from this theory, or the errors to which it has led when hastily

or ignorantly applied: we are only investigating the evidence by which

it is supported. In our former chapters we have drawn out at some

length the line of reasoning which is derived from the character of

the Aqueous Rocks themselves when considered in the light of Nature’s

present operations. We have shown that Stratified Rocks of many

different kinds, just such as those which compose the Crust of the

Earth, have been produced by natural causes within historic times; and

we have explained some of the more simple and intelligible parts of

that complex machinery, which, even now, is busily at work gathering,

sorting, distributing, piling up together, and consolidating the

materials of new strata all over the world. These considerations, as

we took occasion to point out, beget a strong presumption in favor

of Geological theory. Here we have Nature at work, actually bringing

into existence a stratum of rock before our eyes. And there, in the

Crust of the Earth, we find another stratum of precisely the same kind

already finished. What can be more reasonable than to ascribe the one

to the action of the same causes which we see at work upon the other?

And thus, by extending the area of our observations from one class

of Aqueous Rocks to another, the idea gradually grows upon us that

these rocks have been spread out, stratum upon stratum, during many

successive ages, by the agency of secondary causes similar to those

which are still in operation; and that each stratum, in its turn, as it

first came into existence, was for a time the uppermost of the series.

In support of this conclusion we are now about to bring forward a new

and independent argument founded on the testimony of Fossil Remains. An

eminent writer has summed up in a few words the value and importance

of Fossil Remains in reference to Geological theory. “At present,”

he says, “shells, fishes, and other animals are buried in the mud or

silt of lakes and estuaries; rivers also carry down the carcases of

land animals, the trunks of trees, and other vegetable drift; and

earthquakes submerge plains and islands, with all their vegetable and

animal inhabitants. These remains become enveloped in the layers of mud

and sand and gravel formed by the waters, and in process of time are

petrified, that is, are converted into stony matter like the shells

and bones found in the oldest strata. Now, as at present, so in all

former time must the remains of plants and animals have been similarly

preserved; and, as one tribe of plant is peculiar to the dry plain,

another to the swampy morass; as one family belongs to a temperate,

another to a tropical region, so, from the character of the embedded

plants, we are enabled to arrive at some knowledge of the conditions

under which they flourished. In the same manner with animals: each

tribe has its locality assigned it by peculiarities of food, climate,

and the like; each family has its own peculiar structure for running,

flying, swimming, plant-eating, or flesh-eating, as the case may be;

and by comparing Fossil Remains with existing races, we are enabled to

determine many of the past conditions of the world with considerable

certainty.”[68]

On this branch of our subject we do not mean to offer much in the

way of argument strictly so called. We shall content ourselves

with a simple statement of facts, and leave them to produce their

own impression. It will be necessary at the outset to explain some

technical matters, that what we have to say hereafter may be the better

understood: and if in this we are somewhat dry and tiresome, we will

try to make amends by the curious and interesting story of Nature’s

long buried works, which we hope in the sequel to unfold.

* * * * *

When the word _Fossil_ was first introduced into the English language,

it was employed to designate, as the etymology suggests, whatever is

_dug out of the earth_.[69] But it is now generally used in a much

more restricted sense, being applied only to the remains of plants

and animals embedded in the Crust of the Earth and there preserved

by natural causes. When we speak of remains, we must be understood

to include even those seemingly transient impressions, such as

foot-prints in the sand, which having been made permanent by accidental

circumstances, and thus engraved, as it were, on the archives of

Nature, now bear witness to the former existence of organic life.

Now in every part of the world where the Stratified Rocks have been

laid open to view, remains of this kind are found scattered on all

sides in the most profuse abundance. In Europe, in America, in

Australia, in the frozen wastes of Siberia, in the countless islands

scattered over the waters of the Pacific, there is scarcely a single

formation, from the lowest in the series to the highest, that, when it

is fairly explored, does not yield up vast stores of shells, together

with bones and teeth, nay, sometimes whole skeletons of animals; also

fragments of wood, impressions of leaves, and other organic substances.

[Illustration: Fig. 12.--Fossil Irish Deer (County Fermanagh). In the

Museum of Trinity College, Dublin. From Haughton’s Manual of Geology]

These Fossil Remains do not always occur in the same state of

preservation. Sometimes we have the bone, or plant, or shell, in its

natural condition; still retaining not only its own peculiar form and

structure, but likewise the very same organic substance of which it was

originally composed. Examples innumerable may be seen in the British

Museum, or, indeed, in almost any Geological collection: the fine

skeletons of ancient Irish Deer, which are exhibited in the Museum of

Trinity College, Dublin, and of which all the bones are in excellent

preservation, must be familiar to many of our readers.

It happens, however, more frequently that the organic substance itself

has disappeared, but has left an impression on the rock, that now

bears witness to its former presence. Thus, for instance, when a shell

has been dissolved and carried away by water percolating the rock,

it has very often left after it, on the hard stone, a mould of its

outer surface and a cast of its inner surface, with a cavity between

corresponding to the thickness of the shell. In such cases we have

the form, the size, and the superficial markings of the organic body,

but we have no part of its original substance, and no traces of its

internal structure. This form of fossilization, as Sir Charles Lyell

has well put it, “may be easily understood if we examine the mud

recently thrown out from a pond or canal in which there are shells.

If the mud be argillaceous, it acquires consistency in drying, and

on breaking open a portion of it, we find that each shell has left

impressions of its external form. If we then remove the shell itself,

we find within a solid nucleus of clay, having the form of the interior

of the shell.”[70] In many cases the space first occupied by the shell

is not left empty when the shell has been removed, but is filled up

with some mineral substance, such as lime or flint. The mineral thus

introduced becomes the exact counterpart of the organic body which

has disappeared; and has been justly compared to a bronze statue,

which exhibits the exterior form and lineaments, but not the internal

organization nor the substance of the object it represents.

There is a third form more wonderful still, in which Fossil Remains

are not uncommonly found. The original body has passed away as in the

former case, and yet not only does its _outward shape_ remain, but even

its _internal texture_ is perfectly preserved in the solid stone which

has taken its place. This kind of change is exhibited most remarkably

in the vegetable kingdom. Fossil trees of great size have been

discovered of which _the whole substance has been changed from wood

to stone_: yet with such exquisite skill has the change been effected

that the minute cells and fibres, and the rings of annual growth, may

still be clearly traced; nay, even those delicate spiral vessels which,

from their extreme minuteness, can be discerned only by the aid of the

microscope. Thus the tree remains complete in all its parts; but it is

no longer a tree of wood; it is, so to speak, a tree of stone.

The mystery of this extraordinary transformation has not yet been

fully cleared up by scientific men; but the general principle, at

least, is sufficiently understood. It is thus briefly explained by

Sir Charles Lyell: “If an organic substance is exposed in the open

air to the action of the sun and rain, it will in time putrefy, or be

dissolved into its component elements, consisting usually of oxygen,

hydrogen, nitrogen, and carbon. These will readily be absorbed by the

atmosphere or be washed away by rain, so that all vestiges of the dead

animal or plant disappear. But if the same substances be submerged

in water, they decompose more gradually; and if buried in the earth,

still more slowly, as in the familiar example of wooden piles or

other buried timber. Now, if as fast as each particle is set free by

putrefaction in a fluid or gaseous state, a particle equally minute of

carbonate of lime, flint, or other mineral is at hand and ready to be

precipitated, we may imagine this inorganic matter to take the place

just before left unoccupied by the organic molecule. In this manner

a cast of the interior of certain vessels may first be taken, and

afterward the more solid walls of the same may decay and suffer a like

transmutation.”[71] This exposition, so simple and luminous in itself,

may, perhaps, be rendered still more intelligible to the general reader

by an ingenious illustration of Mr. Jukes. “It is,” he says, “as if

a house were gradually rebuilt, brick by brick, or stone by stone, a

brick or a stone of a different kind having been substituted for each

of the former ones, the shape and size of the house, the forms and

arrangements of its rooms, passages, and closets, and even the number

and shape of the bricks and stones, remaining unaltered.”[72]

This singular kind of petrifaction, by which not only the external

form, but even the organic tissue itself, is converted into stone,

has been illustrated, in a very interesting way, by Professor Göppert

of Breslau. With a view to imitate as nearly as he could the process

of Nature, “he steeped a variety of animal and vegetable substances

in waters, some holding siliceous, others calcareous, others metallic

matter in solution. He found that in the period of a few weeks, or even

days, the organic bodies thus immersed were mineralized to a certain

extent. Thus, for example, thin vertical slices of deal, taken from the

Scotch fir, were immersed in a moderately strong solution of sulphate

of iron. When they had been thoroughly soaked in the liquid for several

days, they were dried and exposed to a red heat until the vegetable

matter was burnt up and nothing remained but an oxide of iron, which

was found to have taken the form of the deal so exactly that casts even

of the dotted vessels peculiar to this family of plants were distinctly

visible under the microscope.”[73]

* * * * *

If we have succeeded in making ourselves understood, the reader will

now have a pretty accurate notion of what is meant, in modern Geology,

by Fossil Remains. They are the remains or impressions of plants and

animals, buried in the earth by natural causes, and preserved to our

time in any one of the three forms we have just described. Either

the body itself remains, still retaining its own natural substance,

together with its external form and its internal structure. Or

secondly, the organic substance and the organic structure have both

disappeared, but the outward form and the superficial markings have

been left impressed on the solid rock. Or thirdly, the substance of the

body has been converted into stone, but with such a delicate art, that

it is in all respects, outwardly and inwardly, still the same body,

with a new substance. We should observe, however, that these three

different forms of fossilization, which we have successively described,

are not always clearly distinct in actual fossil specimens, but are

often curiously blended together according as the original organic

substance has been more or less completely displaced, or the process of

petrifaction has been more or less perfectly accomplished.

It will probably have occurred to the intelligent reader that we have

already had some insight into the Fossil world, when investigating the

origin of Organic Rocks. We have seen, for instance, that Coal is the

representative to our age of swamps and forests which once covered the

earth with vegetation; that Mountain Limestone is in great part formed

from the skeletons of reef-building corals; that the White Chalk of

Europe is almost entirely derived from the remains of marine shells.

But it should be observed that these and such like rocks, while they

afford us much valuable information about the ancient organic condition

of our planet, are not, strictly speaking, Fossil Remains. For, not

only does the substance of the organic bodies they represent exhibit

an altered character, but the internal structure has been in great

part effaced, and even the outward forms and superficial markings have

disappeared. They contain, it is true, great multitudes of Fossils.

In the Coal, for example, are found, as we have seen, trunks of trees,

together with the impressions of plants and leaves: in the Chalk and

Mountain Limestone, fragments of shells and corals are often discovered

in a state of perfect preservation. But the bulk of these formations

is made up not so much of Fossil Remains, as of that into which Fossil

Remains have been converted. Coal, for instance, is something more than

Fossil wood; Chalk, and Limestone, and Marble, are something more than

Fossil shells and corals.

Fossil Remains properly so called present a very much more lively

picture of the ancient inhabitants of our Globe. But it is a picture

that can but faintly be conveyed to the mind by the way of mere

verbal description. He who would appreciate aright the reality and

the significance of Fossil Remains must gather his impressions from

actual observation. Let him go, for instance, to the British Museum,

and walk slowly through the long suite of noble galleries which are

there exclusively devoted to this branch of science. He will feel

as if transported into another world, the reality of which he could

scarcely have believed if he had not seen it with his own eyes. Before

him, and behind him, and on each side of him, as he moves along, are

spread out in long array forms of beasts, and birds, and fish, and

amphibious animals, such as he has never seen before, nor dreamt of in

his wildest dreams. Yet much as he may wonder at these strange figures,

he never for a moment doubts that they were once indued with life, and

moved over the surface of the earth, or disported in the waters of

the deep. Nay more, though the forms are new to him, he will be at no

loss, however inexperienced in Natural History, to find many analogies

between the creation in the midst of which he stands, and the creation

with which he has been hitherto familiar. There are quadrupeds, and

bipeds, and reptiles. Some of the animals were manifestly designed to

walk on dry land, some to swim in the sea, and some to fly in the air.

Some are armed with claws like the lion or the tiger, others have the

paddles of a turtle, and others again have the fins of a fish. Here is

an enormous beast that might almost pass for an elephant, though an

experienced eye will not fail to detect an important difference; and

there is an amphibious monster that suggests the idea of a crocodile;

and again a little further on is an unsightly creature which unites

the general characteristics of the diminutive sloth with the colossal

proportions of the largest rhinoceros.

If left to mere conjecture, the visitor would perhaps suppose that

these uncouth monsters had been brought together by some adventurous

traveller from the remote regions of the world. But no: he will

find on inquiry that the vast majority belong to species which for

centuries have not been known to flourish on the Earth; and that many

of the strangest forms before him have been dug up almost from beneath

the very soil on which he stands,--from the quarries of Surrey, of

Sussex, and of Kent, and from the deep cuttings on the many lines of

railway that diverge from the great metropolis of London. The life

they represent so vividly is, indeed, widely different from that which

flourishes around us; but it is the life not so much of a far distant

country as of a far distant age.

It must not be supposed, however, that such skeletons as those which

first arrest the eye in the galleries of the British Museum--so

colossal in their proportions and so complete in all their

details--fairly exhibit the general character of Fossil Remains.

Perfect skeletons of gigantic animals are rarely to be found. They are

the exception and not the general rule,--the magnificent reward of long

and toilsome exploration, or, it may be, the chance discovery that

brings wealth to the humble home of some rustic laborer. Very different

are the common every day discoveries of the working Geologist.

Disjointed bones and skulls, scattered teeth, fragments of shells,

the eggs of birds, the impressions of leaves,--these are the ordinary

relics that Nature has stored up for our instruction in the various

strata of the Earth’s Crust: and these likewise constitute by far

the greater part of the treasures which are gathered together in our

Geological Museums.

We will suppose, then, that the visitor has gratified his sense of

wonder in gazing at the larger and more striking forms, few in number,

that rise up prominently before him, and seem to stare at him in return

from their hollow sockets: he must next turn his attention to the cases

that stand against the walls, and to the cabinets that stretch along

the galleries in distant perspective. Let him survey that multitude of

bones of every shape and size, and those countless legions of shells,

and then try to realize to his mind what a profusion and variety of

animal life are here represented. And yet he must remember that this

is but a single collection. There are thousands of others, public and

private, scattered over England, France, Germany, Italy, and beyond

the Atlantic, on the continent of America, and even in Australia; all

of which have been furnished from a few isolated spots,--scarcely more

than specks on the surface of the Globe,--where the interior of the

Earth’s Crust has chanced to be laid open to the explorations of the

Geologist.

Lastly, before he leaves this splendid gallery, let him take a passing

glance at the Organic Remains of the vegetable world. There is no

mistaking the forms here presented to his view. He will recognize

at once the massive and lofty trunks of forest trees with their

spreading branches; the tender foliage of the lesser plants; and, in

particular, the graceful fern, which cannot fail to attract his eye by

its unrivalled luxuriance. But if the forms are familiar, how strange

is the substance, of this ancient vegetation! The forest tree has been

turned into sandstone; many of the plants are of the hardest flint;

and the rich green of the fern has given place to the jet black color

of coal. Let him take a magnifying glass and scrutinize the internal

structure of these mineralized remains; for the more closely they are

examined the more wonderful do they appear. He can observe without

difficulty their minute cells and fibres, the exact counterpart of

those which may be seen in the plants that are now growing upon the

earth; he may detect the little seed-vessels on the under surface of

the coaly fern; nay, if he gets a polished transverse section of the

sandstone tree, he may count the rings that mark its annual growth, and

tell the age it attained in its primeval forest.

[Illustration: Fig. 13.--Fossil Wood, from the Carboniferous Limestone

of Mayo, showing the rings of Annual Growth.]

[Illustration]

[Illustration]

_CHAPTER XI._

FOSSIL REMAINS--THE EXPLORATION.

_From the museum to the quarry--Fossil fish in the limestone

rocks of Monte Bolca--In the quarries of Aix--In the chalk

of Sussex--The ichthyosaurus or fish-like lizard--Gigantic

dimensions of this ancient monster--Its predatory

habits--The plesiosaurus--The megatherium or great wild

beast--History of its discovery--The mylodon--Profusion

of fossil shells--Petrified trees erect in the limestone

rock of Portland--Fossil plants of the coal measures--The

sigillaria--The fern--The calamite--The lepidodendron--Coal

mine of Treuil--Fossil remains afford undeniable evidence

of former animal and vegetable life--Their existence cannot

be accounted for by the plastic power of nature--Nor can it

reasonably be ascribed to a special act of creation._

From the galleries of the Museum we must now descend into the

subterranean recesses of the mine and the quarry. For it is not enough

to be familiar with the appearance of Fossil Remains, as they are laid

out for show by human hands: we must see them also as they lie embedded

in the successive strata of the Earth’s Crust, which are the shelves

of Nature’s cabinet. We shall begin with the celebrated quarries of

Monte Bolca, in Northern Italy, not far from Verona. Here, in the hard

limestone rock, fifty miles from the nearest sea, entire skeletons

of many different species of fish are found embedded in profuse

abundance, and in a wonderful state of preservation. They lie parallel

to the layers of the rock; and, though flattened by pressure, still

retain their scales, bones, fins, nay, even their muscular tissue,

undisturbed and unharmed. Their color is a deep brown, which forms

a remarkable contrast with the creamy hue of the limestone in which

they are enveloped. The quarries have been worked only by students of

Natural History for the sake of Organic remains, and are, therefore,

of very limited extent; yet so abundant are these fossil treasures

that upward of a hundred different species have been discovered,

and thousands of specimens have been dispersed over the cabinets

of Europe. So closely are they sometimes packed together that many

individuals are contained in a single block.

[Illustration: Fig. 14.--Platax Papilio.

From the limestone of Monte Bolca.]

[Illustration: Fig. 15.--Semiophorus Velicans. From the limestone of

Monte Bolca.]

From these facts Geologists have been led to conclude:--that the

strata in question were deposited on the bed of an ancient sea in

which these fishes swam; that the waters of the sea were suddenly

rendered noxious, probably by the eruption of volcanic matter; that the

fishes in consequence perished in large numbers, and were then almost

immediately embedded in the calcareous deposits of which the strata

are composed. These views receive no small confirmation from a very

remarkable phenomenon to which we may be allowed, in passing, to call

attention. In the year 1831 a volcanic island was suddenly thrown up in

the Mediterranean between Sicily and the African coast; and the waters

of the sea were at the same time observed to be charged with a red mud

over a very wide area, while hundreds of dead fish were seen floating

on the surface. Is it not pretty plain that when the mud subsided many

of the fish were enveloped in the deposit, and thus preserved to future

times? If so, then, we should have an exact modern parallel to the

fossil fishes of Monte Bolca. But for the present it is our purpose

rather to describe facts than to develop theories.[74]

Near the town of Aix, the ancient capital of Provence, in the south

of France, is a group of strata, consisting chiefly of Conglomerate,

Marl, Gypsum, and Limestone, which has earned for itself no small fame

in the annals of Geology. Besides many curious relics of an extinct

vegetation, these strata yield also an abundance of Fossil Insects,

which emerge from the rocky bed in which they have slept for ages, with

a surprising freshness and a life-like reality. But the quarries of

Aix, like those of Monte Bolca, are chiefly famous for their Fossil

Fish. And in this case, too, as in the former, it would seem as if vast

multitudes had suddenly perished together from some mysterious cause,

and were then as suddenly entombed. They exhibit no mark of mechanical

violence: and yet they are found, not unfrequently, crowded together

as closely as they can fit, in every variety of position, on the same

slab of limestone. A good example of such a block is represented in our

woodcut.

[Illustration: Fig. 16.--Fossil Fish from Aix.]

The White Chalk Rock of Sussex has been rendered classical to the

students of Geology by the skilful and laborious researches of the late

Doctor Mantell. Previous to his time the Fish of the Chalk were known

only by their teeth and bones, which abounded in every quarry. But he

succeeded in bringing to light many whole skeletons, and disengaging

them without injury from their chalky envelopment. In many cases these

Fossil Fish appear to have suffered little from compression: the body

still retains its rounded form; and even the most delicate scales and

fins are as little disturbed or distorted as if the original had been

surrounded by soft Plaster of Paris while floating in the water. For

many years Doctor Mantell devoted himself, with indefatigable zeal,

to the gathering of these interesting remains; and his magnificent

collection now adorns the Galleries of the British Museum. In the

annexed illustration is figured a specimen belonging to one of the

most abundant species. It is closely allied to the common perch; and

is popularly called Johnny Dory by the quarrymen of Sussex, but is

entitled Beryx Lewesiensis by the learned.[75]

[Illustration: Fig. 17.--Beryx Lewesiensis, from the Chalk, near Lewes.]

From Fossil Fish we now turn to Fossil Reptiles. Many of our readers

have, perhaps, heard or read something about an important group of

rocks known by the name of the Lias. This formation is well developed

in England, and has received much attention from Geologists. It

stretches in a belt of varying width from Whitby on the coast of

Yorkshire to Lyme Regis on the coast of Dorsetshire; passing in its

course through the counties of Leicester, Warwick, Gloucester, and

Somerset. It is composed chiefly of Limestone, Marl, and Clay; and is

celebrated for the number and size of its great Fossil Reptiles. Of

these the most remarkable is the Ichthyosaurus or Fish-like Lizard.

This monster of the ancient seas combined, as its name denotes, the

essential characters of a reptile with the form and habits of a fish.

No such creature has been known to exist within historic times;

nevertheless, all the various parts of its complicated structure

have their analogies, more or less perfect, in the present creation.

It had the head of a Lizard, the beak of a Porpoise, the teeth of a

Crocodile, the back bone of a Fish, and the paddles of a Whale. In

length it sometimes exceeded thirty feet; it had a short thick neck,

an enormous stomach, a long and powerful tail. This last appendage,

together with four great paddles or fins, constituted the chief organs

of motion. But of all its parts the head was perhaps the most wonderful

and characteristic. In the larger species the jaws were six feet long,

and were armed with two rows of conical sharp-pointed teeth,--a hundred

below, a hundred and ten above. The cavities in which the eyes were set

measured often fourteen inches across, and the eyeballs themselves must

have been larger than a man’s head.

Now what we want particularly to impress upon our readers is, that

the remains of this singular aquatic reptile abound throughout the

whole extent of the Lias Formation in England. Far down below the

surface of the earth they are found embedded in the marls, and clays,

and limestones of Dorsetshire, and Gloucester, and Warwick, and

Leicester, and Yorkshire. Sometimes whole skeletons are found entire,

with scarcely a single bone removed from the place it occupied during

life; but more frequently the scattered fragments are found lying

about in a state of confused disorder; skulls, and jaw-bones, and

teeth, and paddles, and the joints of the vertebral column and of the

tail. The neighborhood of Lyme Regis is a perfect cabinet of these

curious treasures. In some of the specimens there exhumed, a singular

circumstance has been observed, which is deserving of special notice.

We should naturally have expected, from the prodigious power of this

animal, from the expansion of his jaws and the immense size of his

stomach, that he preyed upon the other fish and reptiles that had the

misfortune to inhabit the waters in which he lived. And so indeed it

was. For here enclosed within his vast ribs, in the place that once was

his stomach, are still preserved the remains of his half-digested food;

and amidst the débris we can distinguish the bones and scales of his

victims. Nay, in some of the more colossal specimens of this ancient

monster, we can distinctly recognize the remains of his own smaller

brethren; which, though less frequent than the bones of fishes, are

still sufficiently numerous to prove that, when he wanted to appease

his hunger, he did not even spare the less powerful members of his own

species.[76]

[Illustration: Fig. 18.--Ichthyosaurus Platyodon. Museum of Trinity

College, Dublin. Found in the Lias of Lyme Regis, Dorsetshire.]

[Illustration: Fig. 19.--Ichthyosaurus Communis. Museum of Trinity

College, Dublin. Found in the Lias of Lyme Regis, Dorsetshire.]

It is with facts like these, which are revealed by the Crust of the

Earth all over the world, that Geologists are called upon to deal. When

they meet with skeletons and bones such as we have been describing,

buried deep in the hard rock, hundreds of feet beneath the green grass,

and the waving corn, they cannot help but ask the question: Where did

these creatures come from? When did they live? And by what revolutions

were they embedded here, and lifted up from beneath the waters of the

deep?

In the same formation are found the remains of another ancient

reptile, called the Plesiosaurus, that is to say, nearly allied to

the Lizard. Of this extraordinary monster Cuvier observed that its

structure was the most singular and anomalous that, up to his time,

had been discovered amid the ruins of the ancient world. It is

chiefly distinguished from the Ichthyosaurus, to which it has no small

affinity, by the enormous length of its neck, which, in some species,

resembles the body of a serpent. Dr. Buckland tells us that in the

Plesiosaurus Dolichodeirus the neck is longer than the trunk; the one

being five times, the other only four times, as long as the head. Our

illustration, for which we are indebted to the kindness of Doctor

Haughton, represents a fine specimen of Plesiosaurus Cramptonii, which

was found in the Lias Beds of Kettleness, near Whitby, in Yorkshire,

and which is now a prominent object in the Museum of the Royal Dublin

Society.

The habits and character of the Plesiosaurus have been thus sketched

out by Mr. Conybeare:--“That it was aquatic is evident, from the form

of its paddles; that it was marine is almost equally so, from the

remains with which it is universally associated; that it may have

occasionally visited the shore, the resemblance of its extremities to

those of the turtle may lead us to conjecture. Its motion, however,

must have been very awkward on land; its long neck must have impeded

its progress through the water; presenting a striking contrast to the

organization which so admirably fits the Ichthyosaurus to cut through

the waves. May it not therefore be concluded (since, in addition to

these circumstances, its respiration must have required frequent access

of air), that it swam upon or near the surface; arching back its long

neck like the swan, and occasionally darting it down at the fish which

happened to float within its reach. It may perhaps have lurked in shoal

water along the coast concealed among the sea-weed, and raising its

nostrils to a level with the surface from a considerable depth, may

have found a secure retreat from the assaults of dangerous enemies;

while the length and flexibility of its neck may have compensated for

the want of strength in its jaws, and its incapacity for swift motion

through the water, by the suddenness and agility of the attack which

they enabled it to make on every animal fitted for its prey, which came

within its reach.”[77]

[Illustration: Fig. 20.--Plesiosaurus Cramptonii. Museum of the Royal

Dublin Society.]

The Pampas of South America are not less famous in Geology for the

remains of Gigantic quadrupeds, than the Lias of England for its

colossal marine reptiles. These vast undulating plains, which present

to the eye for nine hundred miles a waving sea of grass, consist

chiefly of stratified beds of gravel and reddish mud; and it is in

these beds that the remains of many unshapely but powerful terrestrial

animals have been found embedded. So abundant are they, that it is said

a line drawn in any direction through the country would cut through

some skeleton or bones. Indeed, Mr. Darwin is of opinion that the whole

area of the Pampas is one wide sepulchre of these extinct animals.

It will be enough for our purpose to describe one in particular,

which, from its prodigious bulk, has received the appropriate name of

Megatherium, or the Great Wild Beast.

The Megatherium, like the Ichthyosaurus and the Plesiosaurus, had

many affinities with the existing creation. In its head and shoulders

it resembled the sloth which still browses on the green foliage of

the trees in the dense forests of South America; while in its legs

and feet it combined the characteristics of the Ant-Eater and the

Armadillo. But it was eminently distinguished from these and all the

other modern representatives of the family to which it belonged by

its colossal proportions. It was often twelve feet long and eight

feet high; its fore-feet were a yard in length and twelve inches in

breadth, terminating in gigantic claws; its haunches were five feet

wide, and its thigh bone was three times as big as that of the largest

elephant. “His entire frame,” as Dr. Buckland has admirably observed

and carefully demonstrated, “was an apparatus of colossal mechanism,

adapted exactly to the work it had to do; strong and ponderous, in

proportion as this work was heavy, and calculated to be the vehicle of

life and enjoyment to a gigantic race of quadrupeds, which, though they

have ceased to be counted among the living inhabitants of our planet,

have, in their fossil bones, left behind them imperishable monuments

of the consummate skill with which they were constructed,--each limb,

and fragment of a limb, forming co-ordinate parts of a well adjusted

and perfect whole; and through all their deviations from the form and

proportions of the limbs of other quadrupeds, affording fresh proofs

of the infinitely varied and inexhaustible contrivances of Creative

Wisdom.”

“This Leviathan of the Pampas, as it has been justly called, became

first known in Europe toward the close of the last century. In the year

1789 a skeleton was dug up, almost entire, about three miles southwest

of Buenos Ayres, and was presented by the Marquis of Loreto to the

Royal Museum at Madrid, where it still remains. Since that time other

specimens, besides numerous fragments, have been discovered, chiefly

through the zeal and energy of Sir Woodbine Parish; by the aid of which

the form, structure, and consequently the habits of this clumsy and

ponderous animal have been fully ascertained. The complete skeleton

which forms so prominent an object of attraction in the British Museum,

and which is represented in the woodcut on the adjoining page, is

only a model; but it has been constructed with great care from the

original bones, some of which are to be found in the wall-cases of the

same room, and others in the Hunterian Museum of the Royal College of

Surgeons.”[78]

[Illustration: Fig. 21.--The Megatherium. From the British Museum.

Length 12 feet; Height 8 feet.]

Closely allied to the Megatherium, but somewhat less colossal in its

dimensions, is the Mylodon. Its remains are found associated with those

of the Megatherium and other great animals of the same family, in

the superficial gravels of South America. A splendid specimen, which

measures eleven feet from the fore part of the skull to the end of the

tail, was dug up, in the year 1841, a few miles north of Buenos Ayres.

It is well figured in the adjoining woodcut, which we reproduce, by

kind permission of the Author, from Dr. Haughton’s admirable Manual of

Geology.

[Illustration: Fig. 22.--Mylodon Robustus, from Buenos Ayres.]

Passing from the petrified fish, and the reptiles, and the quadrupeds,

that thus come forth, as it were, from their graves to bring us tidings

of an extinct creation, we must next turn our attention for a moment to

Fossil Shells. These relics of the ancient world, which are scattered

with profuse abundance through all the strata of the Earth’s Crust,

may seem, indeed, of little value to the careless observer; but to

the practised eye of science they are full of instruction. They have

been aptly called the Medals of Creation; for, stamped upon their

surface they bear the impress of the age to which they belong; and they

constitute the largest, we may say, perhaps, the most valuable part of

those unwritten records from which the Geologist seeks to gather the

ancient history of our Globe.

As regards the prodigious abundance of Fossil Shells preserved in

the Crust of the Earth, it is unnecessary for us here to speak. We

have already seen that the great mass of many limestone formations is

composed almost exclusively of such remains, broken up into minute

fragments, and more or less altered by chemical agency; and besides,

there are quarries within the reach of all, where they may collect

at pleasure these interesting relics of the olden time. But there

are one or two facts of peculiar significance connected with Fossil

Shells, which it may be useful briefly to set down. In the first place,

we would remind our readers that there is a marked and well-known

difference between the shells of those animals that can live only in

the sea, of those that inhabit rivers, and of those, finally, that

frequent the brackish waters of estuaries. Now it has been made clear

beyond all reasonable doubt, by the explorations of Geologists, that

sea-shells abound in great numbers far away from the present line

of coast, in the heart of vast continents. And they are found, not

merely on the surface, but buried deep in the Crust of the Earth, and

overlaid, in many cases, by numerous strata of solid rock, thousands

of feet in thickness. It is also to be observed that they occur at

all heights above the level of the ocean; having been discovered at an

elevation of eight thousand feet in the Pyrenees, ten thousand in the

Alps, thirteen thousand in the Andes, and above eighteen thousand in

the Himalaya.[79] Such are the phenomena which are constantly forcing

themselves on the attention of the Geologist, and which involve a

number of problems that he cannot help attempting to investigate and

explain. He is instinctively impelled to ask himself, how can the

shells of marine animals have come to exist so far away from the sea?

how have they been buried in the Crust of the Earth? how have they been

lifted up to the highest pinnacles of lofty mountains?

Our subterranean exploration would be incomplete if it did not

illustrate the Vegetable as well as the Animal Life of the ancient

world. Let the reader then descend in fancy into the celebrated

quarries of Portland on the south coast of England, and he will see

the fossilized remains of a long past vegetation exhibited in a

very striking manner. In one, of these quarries a vertical section,

extending from the surface downward to the depth of about thirty feet,

presents the following succession of strata arranged in horizontal

layers:--first, a light covering of vegetable soil, beneath which are

thin beds of cream-colored limestone, forming a stratum of solid rock

ten feet thick; then a bed of dark-brown loam, mixed with rounded

fragments of stone, and varying in thickness from twelve to eighteen

inches. This is known to the quarrymen by the name of Dirt-bed, and

seems, in former ages, to have supported a luxuriant vegetation; for

all around are scattered the petrified fragments of an ancient forest.

The prostrate stems and shattered branches of great trees are met at

every step; but what is most striking and peculiar is, that, in many

cases, the petrified stumps are still standing erect, with their roots

fixed in the thin stratum of loam, and their trunks stretching upward

into the hard limestone rock. Immediately below the Dirt-bed is another

thick stratum of limestone, and below this again is a stratum of the

famous Portland stone, so highly prized for building purposes. As the

quarries of Portland are worked chiefly for the sake of this building

stone, little attention is paid to the Dirt-bed and its contents, which

are commonly thrown aside by the quarrymen as rubbish.

[Illustration: Vegetable soil.

Fresh-water Limestone.

Clay.

Laminated fresh-water Limestone.

Dirt-bed with fossil trees and plants.

Fresh-water Limestone.

Bed of Clay.

Portland building-stone full of marine shells.

Fig. 23.--Section of a Quarry in the Island of Portland. Total

thickness about thirty feet.]

The scene of this petrified forest is thus described by Doctor

Mantell:--“On one of my visits to the island the surface of a large

area of the Dirt-bed was cleared preparatory to its removal, and the

appearance presented was most striking. The floor of the quarry was

literally strewn with fossil wood, and before me was a petrified

forest, the trees and plants, like the inhabitants of the city in

Arabian story, being converted into stone, yet still remaining

in the places which they occupied when alive! Some of the trunks

were surrounded by a conical mound of calcareous earth, which had,

evidently, when in the state of mud, accumulated round the roots. The

upright trunks were generally a few feet apart, and but three or four

feet high; their summits were broken and splintered, as if they had

been snapped or wrenched off by a hurricane at a short distance from

the ground. Some were two feet in diameter, and the united fragments

of one of the prostrate trunks indicated a total length of from thirty

to forty feet; in many specimens portions of the branches remained

attached to the stem.”[80]

The Coal Measures of Europe and America offer to the student of Geology

a boundless field for the investigation of Fossil Plants and Trees.

We have already had occasion to notice the Sigillaria. This ancient

tree, remarkable for its beautiful sculptured stem, has no exact

representative in the vegetable kingdom of the present day. But it

abounds everywhere in the Coal Measures; and there seems little doubt

that several great seams of Coal are composed almost entirely of its

carbonized remains. Indeed the ancient soil, which commonly constitutes

the floor on which the bed of Coal reposes, is often as thickly crowded

with the branching roots of the Sigillaria, as the soil of a dense

forest with the roots of the trees by which it is covered. The stem

itself, when converted into Coal, generally assumes the form of long

narrow slabs; having been flattened by pressure during the process of

mineralization. Sometimes, however, it is found uncompressed and erect.

In this case the interior of the trunk is usually observed to have been

filled up with sand or clay: and thus the forest tree, still retaining

its external shape and character, is transformed into a cylindrical

shell of carbonized bark without, and a solid cylinder of sandstone or

shale within. An interesting example is exhibited in our illustration,

Figure 11.

Every Coal mine, too, is adorned with the imprint of the graceful Fern,

which constitutes one of the most attractive features in the Flora of

the ancient world. Not unfrequently it assumes a tree-like character,

as it often does even now in tropical countries; and then, indeed, it

is an object of striking beauty, reaching to a height of forty or fifty

feet, and expanding at the summit into an elegant canopy of foliage.

[Illustration: Fig. 24.--Calamites Nodosus. From the Coal Measures of

Newcastle.]

The Calamite is another plant in which the Coal abounds. Its true

botanical character is not yet clearly ascertained; but it bears a

general resemblance, except for its gigantic dimensions, to the common

Horse-tail of our swamps and marshy grounds. It is a reed-like, jointed

stem, sometimes thirty feet in length, hollow within, and curiously

jointed without.

[Illustration: Fig. 25.--Lepidodendron Sternbergii; a Fossil Tree, 39

feet high. From a Coal Mine near Newcastle.]

Scarcely less conspicuous than the Sigillaria, the Fern, and the

Calamite, is the Lepidodendron or Scaly Tree, one of the most curious

and interesting among the plants of the Coal-bearing period. Like the

Sigillaria and the Calamite, it has been, and still is, a puzzle to

the student of Botany. But it needs not the eye of science to see that

it is unmistakably a stately forest tree, shut up in the Crust of the

Earth, encased in a solid framework of indurated Shale, or Sandstone,

or Coal, as the case may be, and overlaid with massive strata of rock

hundreds of feet in thickness. Such a specimen as that represented

in our woodcut was laid bare some years ago in Yarrow Colliery, near

Newcastle.

[Illustration: Fig. 26 Lepidodendron Elegans. Portion of Stem and

branches; Coal Mine, Newcastle.]

In the same neighborhood was found a portion of the stem and branches

of another variety, Lepidodendron Elegans, which will enable the reader

to form a more complete idea of the appearance presented by this

ancient tree as it stood in its primeval forest.

An unusually favorable illustration of our present subject may be

seen at the colliery of Treuil, in France, not far from the city of

Lyons. The beds of Coal are overlaid by a kind of slaty sandstone,

ten feet thick; and this sandstone is traversed by the vertical stems

of enormous petrified plants, chiefly Calamites. Here, then, to all

appearance, we have an ancient forest enveloped in sandstone. We must

suppose that the forest was submerged while the trees were still erect;

that in this condition it received the sedimentary deposits carried

down by the current of some great river; and finally, that these

deposits were, in the course of ages, compacted into sandstone by a

process already explained. It would seem that after the sandstone had

been partially, at least, consolidated, it was subjected to a sliding

movement here and there, by which the continuity of the stems was

broken; the upper part being pushed on one side, as shown in our Figure.

[Illustration: Fig. 27.--Section of a Coal sandstone at Treuil, near

Lyons. Showing the erect position of Fossil Trees. (Alex. Brongniart.)]

It is time we should bring to a close our survey, meagre and imperfect

as it is, of Fossil Remains. Those who desire to pursue the inquiry

for themselves will easily find an opportunity of doing so. There are

few, we should suppose, who may not, occasionally, have access to one

or other of those splendid Museums of Geology, which have been set up

in all the great towns of Europe. And the still more extensive cabinets

of Nature’s Museum, spread out beneath our feet, are within the reach

of all.

But even the scanty facts which have been set forth faithfully, we

trust, though perhaps feebly, in these pages, are sufficient to satisfy

all reasonable minds that the bones, the skeletons, the trunks and

branches of trees, which have been exhumed from the Stratified Rocks

are really the remains of Organic Life that once flourished on the

earth, or in the waters of the ancient seas. Obvious, however, as this

fact must appear to all who have fully realized the character and

appearance of Fossil Remains, it has been often vigorously assailed and

vehemently denounced. In the early days of Geology phenomena of this

kind were ascribed, not uncommonly, to the “plastic power of Nature,”

or to the influence of the stars. Such notions, however, meet with

little support among modern writers. They were nothing more than wild

fancies, without any foundation either in the evidence of facts or

in the analogy of Nature. The “plastic power of Nature” was a phrase

that sounded well, perhaps, in the ears of unreflecting people; but no

one ever undertook to show that Nature really possesses that “plastic

power” which was so readily imputed to her. No one ever undertook to

show that it is the way of Nature to make the stems, and branches,

and leaves of trees, without the previous process of vegetation; or

to make bones and skeletons which have never been invested with the

ordinary appendages of flesh and blood. Yet surely this is a theory

that requires proof; for all our experience of the laws of Nature

points directly to the opposite conclusion. And as for the influence of

the stars, we may be content to adopt the language of the celebrated

painter Leonardo da Vinci:--“They tell us that these shells were

formed in the hills by the influence of the stars; but I ask where

in the hills are the stars now forming shells of distinct ages and

species? and how can the stars explain the origin of gravel occurring

at different heights and composed of pebbles rounded as if by the

action of running water? or in what manner can such a cause account for

the petrifaction in the same places of various leaves, sea-weeds, and

marine crabs?”[81]

In modern times the form of objection has been somewhat changed. We

are told by some writers that, when we seek to explain the existence

of Fossil Remains by the action of natural laws, we seem to forget the

Omnipotence of God. They urge upon us, with much solemnity, that He

could have made bones, and shells, and skeletons, and petrified wood,

though there had been no living animal to which these bones belonged,

and no living tree that had been changed into stone. And if He made

them, might He not disperse them up and down through His creation, on

the lofty mountains, in the hidden valleys, and in the profound depths

of the sea? and buried them in limestone rocks and in the soft clay?

and arranged them in groups, or scattered them in wild confusion as He

best pleased?

To this line of argument we must be content to reply, that we have no

wish to limit the power of God. But we have learned from our daily

experience that in the physical world He is pleased to employ the

agency of secondary causes; and when we know that for many ages a

certain effect has been uniformly produced by a certain cause, and not

otherwise, then if we again see the effect, we infer the cause. When

a traveller in the untrodden wilds of Western America, comes upon a

forest of great trees, or a herd of unknown animals, surely he never

thinks of supposing that the wild beasts and the forest trees came

directly from the hand of the Creator, in that state of maturity in

which he beholds them. And why? for it might be argued that the power

of God is unbounded, and he might have created them as they now are

if He had so pleased. Is it not that the traveller is impelled, by an

instinct of his nature, to interpret the works of God which he now

sees for the first time, according to the analogy of those with which

he has been long familiar? Now this is just the principle for which we

are contending. According to all our experience of the works of God

in the physical world, the living body comes first, and the skeleton

afterward; the living tree comes first, and afterward the prostrate

trunk and the splintered branches. Therefore when we meet with a

skeleton, we conclude that it was once a living body; and when we find

the petrified stems, and branches, and leaves of trees, we have no

doubt that they are the remains of an ancient vegetation.

But, in truth, if any one, with all the facts of the case fully before

his mind, were deliberately to adopt this theory, that Fossils, as

we find them now, were created by God in the Crust of the Earth, we

candidly confess we have no argument that we should think likely to

shake his conviction; just as we should be utterly at a loss if he

were to say that the Pyramids of Egypt, or the colossal sculptures

of Nineveh, or the ruins of Baalbec, were created by God from the

beginning. The evidence of human workmanship is certainly not more

clear in the one case than is the evidence of animal and vegetable

life in the other. We believe, however, that no such persons are

to be found; that theories of this kind have their origin, not so

much in false reasoning, as in imperfect knowledge of facts; and we

have, therefore, judged it most expedient not to spend our time in a

discussion of philosophical axioms, but to set forth the facts, and

leave them to speak for themselves.

[Illustration]

_CHAPTER XII._

GEOLOGICAL CHRONOLOGY--PRINCIPLES OF THE SYSTEM EXPLAINED AND DEVELOPED.

_Significance of fossil remains--Science of

Palæontology--Classification of existing animal

life--Fossil remains are found to fit in with this

classification--Succession of organic life--Time in Geology not

measured by years and centuries--Successive periods marked by

successive forms of life--The Geologist aims at arranging these

periods in chronological order--Position of the various groups

of strata not sufficient for this purpose--It is accomplished

chiefly through the aid of fossil remains--Mode of proceeding

practically explained--Chronological table._

The existence of Fossil Remains is, then, a fact. Go where you will

through the civilized world, and every chief town has its Museum, into

which they have been gathered by the zeal and industry of man; descend

where you can into the Crust of the Earth,--the quarry, the mine,

the railway cutting,--and there, notwithstanding the plunder which

has been going on for two centuries or more, you will find that the

inexhaustible cabinets of Nature are still teeming with these remains

of ancient life.

When we are brought, for the first time, face to face with these

countless relics of a former world, we are impressed with a sense of

wonder and bewilderment. That the skeletons before us, though now dry

and withered, were once animated with the breath of life; that the

trees now lying shattered and prostrate, and shorn of their branches,

once flourished on the earth, we cannot for a moment hesitate to

believe. But beyond this one fact, all is darkness and mystery. These

gaunt skeletons, these uncouth monsters, these petrified forests, are

silent, lifeless, as the rocks within whose stony bosoms they have

lain so long entombed. Had they speech and memory, they could tell us

much, no doubt, of that ancient world in which they bore a part, of

its continents, and seas, and rivers, and mountains; of the various

tribes of animals and plants by which it was peopled; of their habits

and domestic economy; how they lived, how they died, and how they

were buried in those graves from which, after the lapse of we know

not how many ages, they now come forth into the light of day. As it

is, however, we can but gaze and wonder. We have nothing here but the

relics of death and destruction: there is no feeling, no memory, no

voice, in these dry bones; no living tenant in these hollow skulls, to

recount to us the history of former times.

So thinks and reasons the ordinary observer. But far different is the

language of the Geologist. These dry and withered bones, he tells us,

_are_ gifted with memory and speech; and, though the language they

speak may seem at first unfamiliar and obscure, it is not, on that

account, beyond our comprehension. Like the birds, reptiles, fish, and

other symbols, inscribed on the obelisks of ancient Egypt, these bones

and shells stored up in the Crust of the Earth, have a hidden meaning

which it is the business of Science to search out and explain. They are

Nature’s hieroglyphics, which she has impressed upon her works to carry

down to remote ages the memory of the revolutions through which our

Globe has passed; and when we come to understand them aright, they do

unfold to us the story of that ancient world to which they belonged.

The interpretation of Fossil Remains is, then, an important department

of Geology. Of late years it has been admitted to the rank of a

special science, under the name of Palæontology, which means, as the

word denotes--παλαιῶν ὄντων λόγος--the science which is concerned

about the organic remains of ancient life. The honor of having been

the first to place this science on a solid basis, in fact we may say

the honor of having brought it into existence, is justly accorded to

the distinguished Cuvier, whose name shed a lustre upon France during

the early years of the present century. It is therefore still in its

infancy; but it has already rewarded the zeal of its students by many

wonderful and unexpected revelations. We purpose in the first place to

examine the principles on which it is founded, and then to take a rapid

glance at the conclusions to which it has led.

At the outset it is worthy of notice that the very existence of Fossil

Remains, buried deep in the Crust of the Earth, forcibly confirms the

Geological theory of Stratified Rocks. These rocks, as the reader will

remember, are said to have been slowly spread out, one above another,

during the lapse of many ages, by the operation of natural causes; and

we have seen how this doctrine is supported by arguments founded on an

examination of the rocks themselves,--of the materials that compose

them, and of the way in which these materials are piled together. Now

let us observe how clearly the testimony of Fossil Remains seems to

point in the same direction.

First, the bones and shells which we now find in such profusion, far

down beneath the superficial covering of the Earth, must have belonged

to animals which, when living, flourished on what was then the surface.

Yet now they are buried in the bosom of the hard rock, and covered over

with beds of solid limestone, and sandstone, and conglomerate, hundreds

and thousands of feet in thickness. How can we explain this fact,

unless we suppose that these animals, when they perished, were embedded

in some soft materials, which afterward became consolidated, and above

which, in the course of ages, more and more matter was deposited, until

at length that lofty pile of strata was produced, beneath which the

remains are now found buried?

Again, it is part of our theory that the formation of Stratified Rocks

took place, for the most part, under water. The Organic Remains,

therefore, which we should naturally expect to find preserved in the

strata of the earth, would be those of aquatic animals; or, if the

remains of land animals were to be looked for, it should be of those

chiefly which live near the banks of rivers and estuaries, and which,

after death, might have been carried down by the current and buried in

the silt and mud with which almost all rivers are charged at certain

seasons of the year. We know as a fact that such animals are buried at

the present day in the Deltas of the Ganges and the Mississippi; and

it would be reasonable to suppose that the same should have occurred

in former ages. Now here again the evidence of Fossil Remains exactly

fits in with our theory. For the vast bulk of them are manifestly the

remains of animals that lived in water: and the terrestrial animals,

comparatively few, whose bones are preserved in the Crust of the Earth,

are such as frequent the banks of great rivers or the marshy swamps of

estuaries.

Thus much we may learn even from a cursory glance at Fossil Remains.

But these curious monuments of ancient times have a deeper meaning,

which cannot be unfolded without a more minute and laborious

investigation. Our readers are aware that all the animals at present

existing on the face of the Earth have been scientifically grouped

together, according to certain well-marked characteristics, into

various Kingdoms, Classes, Genera, and Species. Thus, for example, the

horse and the dog are two different Species, belonging to the same

Class of Mammalia; the eagle and the sparrow are two different Species

of the same Class called Birds. Then again the Class of Mammalia and

the Class of Birds both belong to the one common Kingdom of Vertebrata;

because, though different in many other respects, they agree in this,

that all the members of both Classes have a vertebral or spinal column,

to which the other parts of the internal skeleton are attached.

Now when Cuvier began to examine closely the Organic Remains of former

times, to which his attention was called by the bones dug up in the

gypsum quarries of Montmartre, near Paris, about the close of the last

century, he brought with him to the task a very large acquaintance with

the various forms of life that, in the present age, prevail throughout

the world. And he was greatly struck with the marked difference between

those living animals with which he had been long familiar, and those

with which he now became acquainted for the first time. The more

he extended his researches, the more manifest did this difference

appear; until at last it became quite clear that the great bulk of

the animals whose remains are preserved in the Crust of the Earth,

have no representatives now living on its surface. Nevertheless, he

observed that, though the Species no longer exists, it often happens

that we have still other Species of the same Genus; or if the Genus,

too, be extinct, we have other Genera of the same Class. Here, then,

is the first great truth at which Cuvier arrived, and which has been

since confirmed by extensive observations:--that the animals which

formerly dwelt on this Earth of ours, were, for the most part, widely

different from those by which it is now inhabited: and yet there is a

well-defined likeness between them; that both have been created on a

plan so strictly uniform, that the one and the other naturally find

their place in the same system of classification.

As the science of Palæontology progressed, and new facts were day by

day accumulated, another truth, not less important, was gradually but

certainly developed. In the distribution of Fossil Remains through

the various strata of the Earth, there is a certain order observed,

a certain regular law of succession, which cannot have been the mere

result of chance, and which it is the business of science to unravel

and explain. The facts are these. If we follow a particular set of

strata _in a horizontal direction_, we find that the same fossils

continue to prevail over hundreds of square miles, nay, often over a

space as large as Europe, though beyond certain limits this uniformity

of Fossil Remains will gradually be observed to disappear. But when we

penetrate _in a vertical direction_ through the strata, the forms of

animal and vegetable life that we meet with are constantly changing.

After a few hundred yards at the most, we find ourselves in the midst

of a group of fossils, altogether different from those which we have

passed in the beds above: and so on, as we proceed downward, _each

particular set of strata is found to have an assemblage of fossils

peculiar to itself_.[82]

There can be no reasonable doubt as to the truth of these facts. They

have been established and confirmed by the positive testimony of a

whole host of Geologists, whose researches have extended to all parts

of the globe. And we have besides a kind of negative evidence on the

subject which is scarcely less convincing than the positive. Nothing

is more easy than to refute a universal proposition if it is false. If

it is not a fact that each group of strata, as we proceed downward,

exhibits a collection of Fossils peculiar to itself, the assertion may

be at once disproved by pointing out two or three different groups

with the same Fossils. There are thousands of practical Geologists at

work all over the world, eager for fame; and any one of them would

make his name illustrious if he could overturn a theory so generally

received. Now, when a statement of facts can be easily disproved if

untrue; and when, at the same time, there is a large number of men

whose interest it would be to disprove the statement if possible;

and when it is nevertheless _not_ disproved; this circumstance, we

contend, is a convincing argument that the alleged facts _are_ true.

And such precisely is the case before us. We therefore think it would

be unreasonable not to accept the facts.

Let us next examine what is their significance. Each group of strata,

be it remembered, represents to us the animal life that flourished

on the Earth during the period in which that particular group was

in progress of formation. It is, as it were, a cabinet in which are

preserved for our instruction certain relics or memorials of that age

in the world’s history. Of course it is not a perfect collection; but

only a collection of those remains that chanced to escape destruction,

and by some natural embalming process to be saved from dissolution.

When we learn, then, that there is a marked uniformity in the

assemblage of Fossils that are spread over a large horizontal area, in

any group of strata, we conclude that, when that group was in course

of formation, there was a certain uniformity in the animal life that

extended over the corresponding area of the globe; just as, at the

present day, the same species of animals are found to flourish over

a great part of Europe, or America. And if this uniformity of Fossil

Remains does not extend horizontally to an indefinite distance, this is

precisely what we should have expected from the analogy of the existing

creation: for, when we examine the present distribution of animal life

over the earth, we find a marked diversity to exist between countries

that are removed from one another; as, for instance, between Europe and

Australia.

In the next place, we are told that, as we proceed _downward_ into the

Crust of the Earth, each successive group of strata has an assemblage

of Fossils clearly distinct in character from those of the group above

and of the group below. The conclusion to which this fact points is

obvious enough. If, in the former case, we inferred that the animal

life of any one period, considered in itself, was the same over

extensive areas, in this case we must infer that the animal life of

each successive period was _peculiar to that particular age_; being

altogether distinct in its character from the animal life of the period

that went before and of the period that followed. It would appear,

therefore, as Sir Charles Lyell puts it, “that from the remotest

period there has been ever a coming in of new organic forms, and an

extinction of those which pre-existed on the earth; some species having

endured for a longer, others for a shorter time; while none have ever

reappeared after once dying out.”[83]

Now, from these principles, Geologists have been gradually led to build

up a system of Geological Chronology; in other words, to determine the

order of time in which the numerous groups of strata that make up the

Crust of the Earth have been formed, and thus to fix the age of each

group in reference to the rest. This Chronology is not reckoned by the

common measures of time which are used in history, but rather by the

successive periods during which each group of rocks was in its turn

slowly deposited on the existing surface of the globe. For example,

the Coal-measures that so abound in the North of England are very much

older than the bluish clay of which London is built. But if we ask

what is the difference between the age of the one and of the other,

the answer is given not in days and years and centuries, but in the

number of different Formations that intervened between the two. We are

told that the Coal-measures belong to the Carboniferous Formation;

that this Formation was followed by the Permian, and that again in

succession by the Triassic, the Jurassic, and the Cretaceous; and that,

upon this last was spread out the Eocene, to which the London clay

belongs. Indeed, as regards the precise length of any given period,

Geologists can offer nothing but the wildest conjectures. Some form

their estimates in thousands of years; others in millions. And the

wisest amongst them fairly confess they have no sufficient data to

make an accurate computation. Nevertheless, they are all agreed in

this, that the ages of which the memory is preserved in history, that

is to say, the last six thousand years, are but a small part of one

Geological period. Compared to the voluminous chronicles laid up in the

Crust of the Earth, the records inscribed by human hands constitute but

an insignificant fraction of the world’s history. Our readers will be

glad to learn something of the way in which this startling system of

Geological Chronology is constructed and developed.

At first sight, perhaps, it might be imagined that the order of time

in which the various strata were deposited, can be easily learned from

the relative position in which they lie. Since each stratum, when first

produced, was spread out on the existing surface of the globe, it is

clear that the one which lies uppermost in the series must be the

newest, then that which lies next below, and so on till we reach the

lowest of the pile, which must be the oldest of all. Nothing could be

more satisfactory than this reasoning, if each stratum was spread out

over the whole Earth, and if, after having been once deposited, it was

never afterward removed. We might then regard each stratum as a volume

in the Natural History of the Globe, which, when it was finished, was

laid down upon that which contained the chronicles of the preceding

age; and thus the position of every stratum would be in itself a

sufficient evidence of the age to which it belonged.

But such is not the case. Nowhere does the Crust of the Earth exhibit

a complete series of the Stratified Rocks laid out one above another.

In any given section we can find but a few only of the long series of

groups that are familiar to Geologists. And if we follow them on, in a

horizontal direction, we shall invariably find that some of the strata

will _thin out_ and disappear, while new strata will gradually be

developed between two groups that were before in immediate contact. Let

it be observed, in passing, that this fact fits in most perfectly with

the theory we have been all along defending. The Stratified Rocks were

deposited under water; therefore, the strata of any given period were

not _spread out over the whole Globe_, but at most over those parts

only which, for the time, were submerged. With the next period came a

change in the boundaries of land and water; and the formation of strata

ceased in some localities and began in others: and so on from epoch to

epoch. Thus the areas over which the process has been going on, have

been, in every age, of limited extent, and have been ever shifting

from place to place over the surface of the earth. Moreover, there is

the opposite process of Denudation. Many of the strata deposited in

the depths of the ocean must have been afterward swept away by the

breakers, as they slowly emerged from the waters; or at a later time,

reduced to their original elements, and carried back to the sea, by the

action of rivers, rain, and frost. It should seem, therefore, as well

from the _fact_, which is obvious to any one who will examine it, as

from our _theory_, which harmonizes so completely with the fact, that

the strata which we meet with in any given section of the Earth’s Crust

present to us but a very broken and imperfect series of monuments. They

are, as it were, but odd volumes of a long series, and though they lie

in juxtaposition, they may belong, nevertheless, to Geological epochs

widely removed from each other.

Hence, in order to construct a complete system of Geological

Chronology it is necessary to collect together these odd volumes, as

they may be called, of the Great Geological Calendar, and to assign to

each one its proper place in the series. This difficult and complicated

task is accomplished chiefly by the aid of Fossil Remains. We have

already shown that the Fossil Remains which are found embedded in

each group of strata, represent the organic life of the period during

which that group of strata was in progress of formation. Moreover,

we have seen that each period was marked by the existence of an

animal and vegetable creation peculiar to itself. If, therefore, we

find that the Fossils of two different districts exhibit the same

general character, we may conclude that the beds in which they are

preserved were deposited about the same age, and consequently belong

to the same Geological Period. Whereas, on the other hand, if, within

certain limits, we discover two groups of strata, each of which has

a collection of Fossils totally different from the other, it is a

proof that these two groups were _not_ deposited in the same age, and

must, consequently, be referred to different Epochs of the Geological

Calendar. Let us now see in what manner the practical Geologist

proceeds to apply these general principles.

He takes first some one country, say England, and in that country he

selects some one particular district to begin with. Here he examines

a number of different sections, and makes himself familiar with all

the strata of the neighborhood, and with the order in which they lie.

Let us suppose that he finds three different groups spread out one

above another, and let us call these groups A, B, and C; A being the

lowest, B immediately above A, and C above B. The chronological order

of these strata will be, therefore, A, B, C. He will study next the

Fossil Remains which he finds embedded in each group. For convenience

we may designate the Fossils of A by the letter a, those of B by b,

and those of C by c. Now, according to the principles above explained,

these three collections of Fossils will be specifically distinct from

one another, each collection being characteristic of one particular set

of strata. Our Geologist next goes into a neighboring district, and

there examines a number of sections as before. Let us suppose that he

encounters again the groups A and B. He may, perhaps, have been able

to trace the beds from one district to the other, by observations made

upon his line of route: or it may be that the nature of the country

has rendered such observations impossible; or the observations may

have been so imperfect that from _them_ he could arrive at no certain

conclusion regarding the identity of the strata. But, at all events, if

the new district yield an abundant supply of Fossils, he cannot long

be at a loss. He will recognize the group A by the Fossils a, and the

group B by the Fossils b. An important fact, however, soon attracts his

attention. Group C has entirely disappeared, and is not to be found in

this district; while between A and B there is a new group of rocks that

he has not seen before, with a collection of Fossils different from a,

b, and c. We will call this new group X, and its Fossils x. It is clear

that the formation of X must have intervened between the formation of

A and B; and the chronological order now stands A, X, B, C. In like

manner another district may disclose a fourth group of strata, say Y,

intervening between B and C. The chronological order will then stand A,

X, B, Y, C. And thus the Geologist pursues his explorations until he

has gone through the whole country, and arranged the principal groups

of strata according to the order of time in which they were deposited.

In this way the whole of England has been minutely explored during the

last half century. The task was first undertaken by William Smith,

who is justly called the Father of English Geology. After multiplied

researches, extending over a space of many years, during which he

travelled the whole country on foot, this eminent man published in

1815 his Geological Map of England and Wales with part of Scotland; a

work which is described by Sir Charles Lyell as “a lasting monument of

original talent and extraordinary perseverance.” Hundreds followed in

the same course, exploring every day new districts, and, by the new

facts which they brought to light, supplying what was wanting in the

work of Smith, correcting what was faulty, and confirming what was

true; until at length, in our day, it may be said that the Stratified

Rocks of England are almost as well known and as completely mapped out

as are its counties and its towns, its rivers, lakes, and mountains.

Meanwhile, Geologists were not idle in other parts of the world.

Germany, France, Italy, even many districts of America and

Australia, have been diligently explored according to the same

principles as England. And by a comparison of the observations

made, the Chronological order of strata over a considerable part

of the Earth, but more particularly of Europe, has been now pretty

fairly ascertained. This order we have attempted to set forth in an

intelligible and sensible form by means of the table here annexed.

In the Woodcut are represented the strata hitherto examined by

Geologists, laid out one above another, according to the order of time

in which they are supposed to have been produced. The whole series

is divided into a number of Formations, the names of which are given

in the first column, together with an approximate estimate of their

thickness, in feet. These Formations are distinguished from each other

in the drawing by a difference of shading. Each of them, according

to Geological theory, is believed to have come into existence by the

accumulation of solid matter at the bottom of the sea; and the Period

of time occupied in its production is usually designated by the

same name as the Formation itself. Thus we read of the Carboniferous

Formation and the Carboniferous Period: by the former phrase is meant

certain groups of strata contemporaneously deposited over various parts

of the Earth’s surface; and by the latter, the Period of time during

which these groups of strata were spread out. In like manner, when we

hear of the Carboniferous Fauna and Flora, we are to understand the

animal and vegetable life that flourished during the Carboniferous

Period. And again, when Geologists talk of the Cretaceous sea, and tell

us that it rolled over a great part of what is now called Europe, they

mean to speak of that sea on the bottom of which the Cretaceous rocks

were deposited.

[Illustration: TABLE OF STRATIFIED ROCKS,

CHRONOLOGICALLY ARRANGED.]

Most of the Formations comprise various groups of strata; and these

groups are made up of different varieties of rocks, which are again

divided into layers or beds of varying thickness. Even in these beds

themselves we can often distinguish an indefinite number of laminæ or

plates, scarcely thicker than a sheet of paper, which correspond to

the periodical depositions of matter by which the rock was originally

formed. These numerous subdivisions may be conveniently illustrated

from the Carboniferous Formation. It is divided into two leading groups

of strata; the Mountain Limestone below, the Coal Measures above. The

upper group is the larger as well as the more important. It attains

a maximum thickness in South Wales of 12,000 feet; and consists of

numerous strata of Sandstone and Shale, with thin seams of Coal

occasionally interposed. In one remarkable instance a hundred distinct

layers of Coal, varying in thickness from six inches to ten feet,

have been counted in one Coal-field, each resting on a bed of Shale,

called in mining phraseology the Underclay. This Shale itself naturally

divides into an indefinite number of thin plates, just like the stratum

of mud accumulated by the annual inundations of the river Nile, and

constituting the present soil of Egypt.

We have not attempted to represent in our Woodcut these various

divisions and subdivisions of Stratified Rocks. But the names of some

important and well-known groups we have had engraved, to impress more

vividly on the mind the place to which they are to be referred in the

Geological Calendar. Thus the reader may see at a glance the respective

ages of the Coal and the Chalk; of the Lias, in which are preserved the

remains of extinct gigantic reptiles, and the Glacial Drift, in which

the elephant, the rhinoceros, and the hippopotamus are found entombed;

of the Mountain Limestone, which is often nothing else than vast beds

of Coral uplifted from beneath the waters of the ocean, and the Oolite,

which includes the Portland quarries, where the petrified stems of

ancient forest trees are found standing erect in the solid rock.

As the series of Stratified Rocks is divided by Geologists into a

certain number or systems or Formations, so these are again grouped

into still larger classes, called Primary, Secondary, and Tertiary;

that is to say, first, second, and third, in the order of formation.

These larger classes correspond to the Great Epochs or Ages of

Geological time, each comprising within itself many distinct Periods.

The Primary rocks are also called Palæozoic--παλαιὁν, ancient, and

ξῶον, an organic being--because they contain the oldest forms of

organic life: in like manner the term Mesozoic--μεσον, middle, and

ξῶον--is applied to the Secondary strata, inasmuch as they contain

the middle or intermediate forms of organic life: and the name

Kainozoic--χαινὁν, new, and ξῶον--is given to the Tertiary, which

contain the newest forms of organic life.

The term Post-Tertiary has recently been adopted to designate those

superficial deposits which are subsequent to the Tertiary Age. They are

divided into two groups; the Recent, which corresponds with the period

of history, and the Post-Pliocene which precedes it. Some writers seem

to think that these deposits, being so very insignificant and so very

modern when compared with the long series of Stratified Rocks, are not

truly Geological. But this, we should say, is a mistaken view of the

question. It seems to us that even the minute layer of mud that is

deposited every day at the mouth of the Ganges or the Mississippi, is

linked on to the long chain of events which have brought the Crust of

the Earth into its present condition; and, therefore, truly belongs

to the science of Geology, and is deserving of its proper place in

Geological classification.

We may here observe that the names of the great Geological Epochs are

descriptive names; that is to say, the obvious meaning of the words

corresponds to the character of the strata they are used to represent.

Primary, Secondary, Tertiary, mean First, Second, and Third, in the

order of formation: Palæozoic, Mesozoic, and Kainozoic, signify

that the strata so called are characterized by Ancient, Middle, and

Modern, forms of organic life. But it is very often quite otherwise

with the names of the several Formations: and this is a point of

no small importance to the student of Geology. These names must be

regarded simply _as names_ employed to designate the strata formed in

each successive period, and not exactly to describe their character.

They generally had their origin in some accidental circumstance, or

were derived from some particular locality; and afterward, being

perpetuated, gradually came to receive a much more extended application

than that which the words themselves would seem to suggest. Thus, for

instance, the Cretaceous Formation is so called from the remarkable

stratum of white chalk (creta) which was deposited during that period

over a great part of Europe; but it would be a mistake to suppose that

the whole Formation is made up of chalk. On the contrary, in different

localities it is composed of very different materials; near Dresden,

for example, it is a gray quartzose sandstone, and in many parts of the

Alps it is hard compact limestone.[84] Again, the Devonian Formation

derives its name from Devonshire, where the rocks of the Devonian

period were first minutely examined; but we must not therefore infer

that this Formation is peculiar to the county of Devon; it is to be

found in many other parts of England, also in Ireland, and on the

continent of Europe. So, too, another Formation has received the name

of Carboniferous, which literally means Coal-bearing (carbo fero)

because of the beds of Coal which are sometimes associated with its

strata; yet this Formation is often found quite destitute of Coal over

a very extensive area.

In looking over our Table of strata the reader must have noticed that

the successive spaces in the Woodcut are not proportioned to the

actual thickness of the successive Formations for which they stand.

The Secondary and Tertiary Rocks taken together are scarcely one-third

as thick, in reality, as the Primary; yet they occupy an equal space

in the engraving: and, more remarkable still, the Cretaceous system

is allowed double the space of the Laurentian, though less than half

as thick. This circumstance calls for a passing word of explanation.

In the early annals of a country there is generally a great scarcity

of authentic records; and, from a simple dearth of facts, the history

of a whole century is compressed, not unfrequently, into a few

pages: whereas, in later times, when documentary evidence begins to

accumulate, the historians will often spread out the events of two or

three years over several chapters. Something of the same kind takes

place in Geology. The Fossil Remains, from which, as from authentic

documents, the Geologist chiefly derives his information regarding the

history of the Earth’s Crust, are scanty in the earlier Formations,

and abundant in the more recent. And thus it happens that the older

Geological Periods, notwithstanding the vast thickness of the rocks by

which they are represented, do not occupy a very prominent position

in the annals of Geology, and are compressed into a comparatively

insignificant space in its Tables. Nevertheless, the immense depth of

the earliest Stratified Rocks must be taken into account in any attempt

to estimate the comparative duration of the several Geological Periods.

We have, therefore, set down, under the name of each Formation, an

approximate estimate of its actual thickness, taken chiefly from the

works of Doctor Haughton and Sir Charles Lyell.

Before bringing this chapter to an end we would observe that the

system of classification we have here endeavored to explain does not

pretend to be final and complete. It is, on the contrary, little

more than a temporary expedient to render intelligible the results

at which Geologists have hitherto arrived; and is liable to manifold

modifications in proportion as their acquaintance with the records they

have undertaken to interpret becomes more extensive and more minute.

All that they now contend for is this: that the successive Formations

represent successive Periods of time, which followed one another in

the order here set forth, and during which the Earth was peopled with

certain species of Plants and Animals, for the most part peculiar to

their respective eras.[85]

[Illustration]

_CHAPTER XIII._

GEOLOGICAL CHRONOLOGY--REMARKS ON THE SUCCESSION OF ORGANIC LIFE.

_Summary of the history of stratified rocks--Striking

characteristics of certain formations--Human remains found

only in superficial deposits--Gradual transition from the

organic life of one period to that of the next--Evidence

in favor of this opinion--Advance from lower to higher

types of organic life as we ascend from the older to the

more recent formations--Economic value of geological

chronology--Illustration--Search for coal--The practical man

at fault--The geologist comes to his aid, and saves him from

useless expense._