Chapter IX (1)

STRATIFIED ROCKS OF ORGANIC ORIGIN--ILLUSTRATIONS FROM VEGETABLE LIFE.

_Origin of coal--Evident traces of plants and trees in
coal-mines--Coal made up of the same elements as wood--Beds
of coal found resting upon clay in which are preserved
the roots of trees--Insensible transition from wood to
coal--Forest-covered swamps--Accumulations of drift-wood in
lakes and estuaries--Peat bogs--Beds of Lignite--Seams of
pure coal with half-carbonized trees, some lying prostrate,
some standing erect--Summary of the argument hitherto
pursued--Objection to this argument from the Omnipotence of
God--Answer to the objection._

As animals, by organic action, extract lime from the waters of the ocean they inhabit, which, being converted in the first instance into minute shells, or stony skeletons, afterward passes into a compact and solid rock, so in like manner do plants and trees extract carbon from the atmosphere in which they vegetate, and convert it into coal. No reasonable doubt can now be entertained that coal derives its existence, almost entirely, from the woody tissue of sunken swamps and forests. Though the nature of the process by which this transformation takes place, is yet but imperfectly understood, and is, indeed, at the present moment a subject of much discussion and controversy, nevertheless the _fact_ that the change _has_ taken place is fully accepted by all as an established truth, and is supported by an accumulation of evidence which it is not easy to resist.

The first circumstance to which we shall call attention, is the wonderful profusion of vegetable life that is always associated with coal. Every one who has descended at any time into a coal mine, or who has examined the specimens usually exhibited in a well-furnished museum, must have been struck by the countless forms of trees and plants, which still remain vividly impressed on this black and unsightly mineral. Dr. Buckland has described this phenomenon with much vigor and beauty in his celebrated Bridgewater Treatise: “The finest example I have ever witnessed is that of the coal mines of Bohemia just mentioned. The most elaborate imitations of living foliage upon the painted ceilings of Italian palaces, bear no comparison with the beauteous profusion of extinct vegetable forms with which the galleries of these instructive coal mines are overhung. The roof is covered as with a canopy of gorgeous tapestry, enriched with festoons of most graceful foliage, flung in wild irregular profusion over every portion of its surface. The effect is heightened by the contrast of the coal-black color of these vegetables with the light ground-work of the rock to which they are attached. The spectator feels himself transported, as if by enchantment, into the forests of another world; he beholds trees of forms and characters now unknown upon the surface of the earth, presented to his senses almost in the beauty and vigor of their primeval life; their scaly stems and bending branches, with their delicate apparatus of foliage, are all spread forth before him, little impaired by the lapse of countless ages, and bearing faithful records of extinct systems of vegetation, which began and terminated in times of which these relics are the infallible historians.”

Fig. 9.--Pecopteris Adiantoides. Fig. 10.--Sphenopteris Affinis.

Fossil Ferns found in the Coal Measures of Europe and America.]

The next important fact that points to the vegetable origin of Coal is, that wood and Coal are both composed of the same ultimate elements--carbon, hydrogen, and oxygen. This analogy is the more remarkable when we are told that no other rock except Coal exhibits anything approaching to this composition. It is true that the elements just enumerated do not exist in the same proportions in wood and in Coal. But the difference, when rightly understood, rather tends to confirm our theory that the one is derived from the other. There is more Carbon in Coal than in wood; while there is less oxygen and less hydrogen. To explain how this may have come to pass during the process of transition, we must call in the assistance of the chemist. It appears from the researches of Liebig that, when vegetable matter is buried in the earth, exposed to moisture, and partially or entirely excluded from the air, the process of decomposition sets in, and that under this process carbonic acid gas and carburetted hydrogen gas are slowly evolved. At the same time a portion of the oxygen when set free would naturally enter into a new combination with a portion of the hydrogen, and form water. The result of these several changes would necessarily be, that the accumulation of vegetable matter buried in the earth would part, in course of time, with no small share of its carbon, its hydrogen, and its oxygen, but not with all in the same proportions: for the new combinations would use up more of the oxygen than of the hydrogen, and more of the hydrogen than of the carbon.[58] In other words, if the process should have gone on for a sufficient lapse of ages, these elements would no longer exist together in the proportions which are necessary to constitute wood, but would rather exist in the proportions which are found to constitute coal.[59]

This explanation is confirmed by a fact with which our readers are no doubt familiar. According to the explanation, carbonic acid and carburetted hydrogen are evolved during the process by which coal is produced from wood. We should therefore expect to find these gases closely associated with Coal. If they are _not_ so associated, their absence is a serious objection against our theory; but if they _are_ so associated, their presence is a strong evidence in its favor. Now on this point, as every one knows, practical miners bear testimony that the fact corresponds exactly with our theory. They tell us that reservoirs of Choke-damp, which is carbonic acid, and of Fire-damp, which is carburetted hydrogen, are found very commonly pent up in the crevices and cavities of coal beds, and are the cause, when tapped, of many of the accidents which take place. They even assure us that some beds of coal are so saturated with gas that, when cut into, it may be heard oozing from every pore of the rock, and the coal is called _singing coal_ by the colliers.[60]

To sum up, then, what we have said on this point: it appears, first, that the same constituent elements are found in wood and Coal; secondly, though they do not exist in the same proportions in the two substances, the difference is fully accounted for by the changes which we should naturally expect to take place when large accumulations of vegetable matter are buried in the earth; thirdly, in the hypothesis of these changes, carbonic acid and carburetted hydrogen would certainly be developed; and in point of fact, these gases are found intimately associated with Coal all over the world.

There is another remarkable fact which fits in most admirably with our theory. Coal is found at the present day in the Crust of the Earth, disposed in thin seams or beds, and each bed is almost uniformly found to rest upon a stratum of fine clay, sometimes several feet in thickness. This is just what our theory would lead us to expect. If coal is produced from plants and trees, these plants and trees must have grown upon some suitable soil; and, therefore, in this hypothesis we should expect, ordinarily speaking at least, to find a bed of clay beneath every bed of coal. But this is not all. When we examine more closely the stratum on which the coal reposes, we find the roots and stems of trees mingled with the clay in the greatest profusion. In the Welsh coal field, in a depth of twelve thousand feet, there are from fifty to a hundred beds of coal, each lying on a stratum of clay abounding in these remains.[61]

We now come to an argument of a practical kind which appeals to common sense and common experience. Let us suppose that a person wholly unacquainted with the art of manufacturing paper, were to enter a paper-mill when the workmen are away, and the process of manufacture for a time suspended. At first sight he would probably find it difficult to persuade himself, that the piles of clean white paper, which attract his notice at one end of the building, are produced from the heaps of filthy rags which he sees accumulated at the other. But if he be a sagacious observer, he will soon find evidence to convince him that this is really the case. For he will perceive, upon close examination, that the self-same material is exhibited in every intermediate state of progress from one extreme to the other. First, there is the great chest with its numerous compartments, in which the rags are seen carefully sorted, according to their various degrees of quality and texture. Next comes the fulling-mill, where they are washed and bleached. Then the revolving cylinder, furnished on the exterior surface with sharp blades or cutters; and the vat in which it moves is filled with the rags, which now assume the form of a thin liquid pulp. Advancing still further he will see this pulp evenly spread out upon a wire-gauze frame, and now at last it is beginning to exhibit some likeness to the form and substance of paper. Further on it is seen pressed and dried; and last of all cut into sheets and laid aside in lofty piles.

Now it seems to us that we are placed in somewhat of the same position, as regards the manufacture of Coal. We cannot observe the process actually going on; for though, in this process, the work is never suspended, the workmen never at rest, yet extending as it does over a space of many centuries, it is too slow to be sensible; and besides it is conducted in great part beneath the surface of the Earth. Nevertheless, we can trace the progress of change through each intermediate stage of the transition, from one extreme to the other,--from the primeval swamps and forests through the numerous varieties of the Peat and Lignite to the richest beds of pure Coal.

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.

_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.”

_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.

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.