Waterford on the one hand, and to Dublin on the other.*

Others have belched forth such volumes of ashes, that had the eruption occurred at Mount Blanc, France, Spain, and Germany would have had the sun darkened for three days, and Ireland and Greece would both at once have felt or heard the force of the explosion. Still, even such grand effects as these are but transient and partial; but there are more permanent

ones.

During earthquakes, great countries, with all their weight of mountains and all their bulk, to an unknown depth within the interior of the earth, have been lifted up at one great heave to the amount of several feet; and after slowly settling down again a little, have retained a great part of their elevation. The coast of Chile gives us many well-attested instances of their action, and Mr. Darwin found the proofs of its having occurred many times during past years in the existence of old sea beaches and sea bottoms, on the flanks of the hills at various heights, up to one thousand two hundred feet above the sea.

In the earthquake of January, 1855, in New Zealand, a tract of land as large as Yorkshire was raised from one to nine feet. A little cliff, or scarp, bared of earth, nine feet high, was traced for ninety miles along the margin of the hills at the edge of the plain; and "in consequence of a rise of five feet of the land on the north side of Cook's Straits, near Wellington and Port Nicholson, the tide had been almost excluded from the river Hutt; while, on the north side of the same straits, where the ground has sunk about five feet, the tide now flows eight miles further up the river Wairau than before the earthquake." (Report of a Lecture of Sir C. Lyell to the Royal Institution. Literary Gazette, March 15th, 1856.)

It may reasonably be doubted whether a single earthquake of all the thousands recorded by Mr. Mallett or M. Perey, has ever occurred unaccompanied by some change, however slight, in the level of some portion of the land that has been shaken.

But it is not solely in times of earthquake and disturbance that a permanent change in the level of the land is now taking place. Land is quietly rising, or as quietly sinking unmarked of all men, unless it happen on the borders of the sea. Sweden, Norway, and Lapland, north of the latitude of Stockholm, are undergoing a process of gentle elevation at the rate of five feet in a century at the North Cape, the rate diminishing as we come southwards, till in Scania it appears to be converted into a depression.

The west coast of Greenland for six hundred miles is calmly sinking at such a rate, as that the Esquimaux avoid building even their rude huts at the water's edge, since they know that, although built upon a rock, the rock will be sunk below the sea, before the frail hut perishes.

The

posts on which the Moravian missionaries once hung their skin canoes upon dry land, may be seen now be neath the waters as silent evidences of the depression that has occurred.

If, then, we join to the changes caused by the external atmospheric and aqueous agencies, those thus produced by the internal igneons agencies of our globe, we shall see that we inhabit no inert mass of brute unmoving matter, but rather that we tread upon the surface of a huge slowlymoving self-acting machine, for ever at work in modifying its own external form, and in producing and reproducing the complexities of its own internal structure.

Allow but a sufficient time for the action of this machinery, and we should see the possibility of every part of our present lands having been once under the sea; every part of our present oceans having once been occupied by dry land; every one of our present mountains having been once a plain; and many at least of our present plains having been covered by mountain masses that have been sheared down and pared away, and literally cast into the sea.'

If we turn to the living part of nature, and examine into the history of animals and plants, we should, to our surprise, perhaps, be met with

similarly good evidence of change having taken place in them in our own times; and still gteater changes in times that are long past.

The level of the upper surface of the sea and a few feet above or below it, is the more densely inhabited part of the earth. On land the vertical range of living beings varies with the latitude, being greatest under the equator, where sometimes the very mountain sides swarm with life to a height of several thousand feet. Even here, however, at 15,000 feet, life is excluded by everlasting snow, and becomes more varied and more numerous in proportion as we descend upon the plains and enter the jungles near the level of the sea; while, as we pass through the temperate to the arctic zones, the vertical limits of life become narrowed, first by thousands, and then by hundreds of feet, all above a gradually diminishing altitude being a desert.

Beneath the sea the vertical range of life is even more limited than on land. Fifty fathoms or 300 feet is the depth within which by far the greater part of marine life is included, while beyond twice that depth the dark abysses of the ocean are almost as void of life as the sterile summit, of snow-clad mountains.

Many animals and plants, too, both subaqueous and terrestial, are confined within particular portions of these zones of height and depth. Some few require a considerable altitude on land, or a considerable depth at sea, for their existence.

The lateral or geographical distribution of animals and plants, again, is equally well marked in the sea as on the land. The sea-fish, the shells, the star-fish, the sea-urchins on the opposite coasts of Europe or America -seas separated by great masses of land-are as different from each other, as are the land animals and plants of Europe and America, lands separated from each other by a great sea.

Similar climates in opposite hemispheres are inhabited by different, although representative, species of animals and plants both on land and under water. There was not a single

species of animal, mammal,* bird or insect, not a single species of plant, tree, shrub, or grass in Van Dieman's Land when first visited by Tasman, the same as any British or European species; neither was there a single fish, nor a single shell, nor a crab, lobster, shrimp, star-fish, sea-urchin or polyp, identical with any to be found here; however the colonists may have appended the old names to them. There were, indeed, cockles and oysters and limpets, but not the same cockles and oysters and limpets as we have at home, and the differences are quite sufficient to be perceptible to everyone, when the two kinds come to be compared side by side.

Some species of animals, even of those so easily migratory as birds, are confined within much narrower limits than those we have alluded to. Mr. Darwin tells us that he found peculiar species of birds confined to small islands, even in sight of each other, among the Gallapagos group.

Now if species of animals and plants be confined within certain limits, and the climate or other local circumstances become within those limits unfavourable to the life of that species, it will shortly die out and become extinct.

If, again, the domain occupied by one species be invaded by another hostile to it, the latter will prey upon the former until it become first rare and finally extinct.

Man has extinguished the Dodo of the Mauritius, the Norfolk Island parrot, and, perhaps other animals, utterly, and he has caused other species, to become extinct within certain districts, as, for instance, the wolf, and perhaps, the beaver and others, within the British Islands.

Now geological investigation shows us that there was once a time, when, the present lands of the globe, being much the same as we now find them, the animals inhabiting them were different from what they now are.

Ireland, for instance, was traversed by reindeer, by bears of an extinct species, and by great elks. England, and Europe, and Northern Asia were inhabited by a species of elephant,

with long hair and a woolly coat; by an extinct species of hippopotamus and rhinoceros; by bears, nearly as large as a horse, living in caves into which they dragged their prey; and by hyenas differing from any living hyena, making their dens, through a long series of ages, in the caves of Yorkshire and other places.

.*

During the same period, North America was inhabited by great elephantine animals called mastodons;" South America by gigantic sloths and armadillos, called megatherium, mylodon, glyptodon; India by many extinct species of elephants and other great animals, uniting the elephants and the antelopes; Australia, by large extinct species of kangaroos and wombats; and New Zealand by a gigantic bird allied to the ostrich and the emu. In most cases, especially in the southern hemisphere, these recently extinct animals had a more or less close relationship to the most remarkable kind of animals now living in the quarter of the globe in which they are found.

The remains of many of these animals have been found either buried under the stalagmites of caverns, in the mud of old dried-up lakes, or in the most superficial and recently deposited clays, sands, and gravels now covering the face of the country. In some cases these remains are found associated with sea shells, showing that the present lands were then covered by the sea, or in other words stood then at a lower level than they do now, and thus admitted the sea to flow over what is now the low land.

Deeper and wider research shows us yet more; it proves to us that the solid rocks of which the plains, the hills, nay, even the mountains are themselves composed, are, in the majority of instances, relics of the sea, are nothing but indurated clays, muds, sands, gravels, or limestones, that have been deposited at the bottom of the sea, and are often crowded

by, sometimes almost entirely made up of, the remains of animals that inhabited the sea.

Space compels us to be brief and condensed in what we have yet to say upon this subject.

The crust of the earth is known to be composed of two kinds of rocks, igneous and aqueous. The aqueous are made up of a number of widelyspread but limited beds, each two or three feet thick, and varying in area from a few square feet to several square miles. These beds were deposited successively, now here, now there, side by side, and one upon the other. Fragments of such animals and plants as were living at the time of their deposition were now and then included in these beds, and were mineralised or petrified along with them. The igneous rocks have been from time to time thrust in among them in a molten state, protruded through them and spread over them.

The aqueous rocks have since their deposition been at various times elevated, tilted up, and set more or less completely on edge, so that even the lowest and oldest set of them show their edges occasionally at the surface of the ground. It follows that by diligent search, and widespread and laborious investigation, they may all be eventually examined and described, and that, by little and little, we shall be able to extract from the examination of their physical character and their organic contents, the natural history of the crust of the earth.

This history will be always a fragmentary one. It is a history made out of the examination of ruins and burnt records, and half-defaced inscriptions and old coins. Nevertheless it is a real one as far as it goes. The facts of which the record is preserved cannot be invalidated by the circumstance that the records of many other similar facts are irretrievably lost.

The history is read somewhat in this way. If there be any number

of separate beds of earth (or rock) deposited one upon another, they must have been successively deposited, the divisions between the beds marking intervals or pauses that occurred in the deposition. The lowest are the oldest, and the highest the newest or youngest of the series. Suppose that in making excavations in a ruined city we were to find two pavements, one above another, with a deposit of several feet of earth between them, we should have no hesitation in assuming that we had here the record of a great lapse of time. We should look on the lowest pavement as the oldest, forming part of some very ancient building which some circumstances had caused to be ruined and deserted. The earth which covered it might be either volcanic ash, or mud, or sand, brought in by water. cording to its nature we should attribute its origin to volcanic eruption, to floods of a river, or a lake, or to an incursion of the sea. The second pavement would prove to us the lapse of another period during which other buildings were erected and occupied, for some years at all events. If that were again covered with earth, we should reason about it as in the first

case.

Ac

Now, if we substitute "limestone" for "a pavement," and think of submarine creatures as its constructors, instead of the human race-this is exactly what occurs so frequently in geology. The natural pavements, whether of limestone or other material, differ from the artificial ones in being much more numerous, and much more widely extended. It is the business of the practical geologist to trace these pavements or beds, and lay them down upon maps, so as to mark out their position and their extent, and to arrange and classify them in their natural order of oc

currence.

In doing this he meets with difficulties from several sources. First of all they end irregularly, one in one place and one in another; he has to search for and to mark these endings, therefore, so that he may intercalate the periods they record in their proper places, in his abstracts and his tables. Secondly, they are often much broken, and frequently contorted and bent about, up and down, in various directions, and he has to

trace them out through these disturbed portions, so as not to lose the clue to their original order of date. Lastly, it is only here and there that they can be observed in any natural or artificial excavations, and he has to make himself master of all their characteristics, their points of difference, and points of resemblance, so as to recognise the same beds in separate excavations, and thus draw lines of connection between them.

His researches are facilitated by two sources of assistance. He first of all notes the materials of which the beds are composed, and in the majority of instances he finds these materials to be the same, in the same beds, or in beds of the same date, over very wide spaces. It is as if the architects of different periods had different materials at their disposal, one kind only being available or being in fashion during each period. In consequence, of this the geologist finds often a vast number of pavements, all made of the same peculiar stuff, and all resting directly one upon the other, so that however each separate bed may end or be confined within a small area, the whole bulk of exactly similar beds makes up a thickness of many hundred feet, and spreads over great spaces, sometimes over several large countries. These great masses of similar beds give us good horizons, enabling us at once to distinguish the beds above from those below them, and thus dividing the whole vast series of beds into comparatively few easily recognisable groups.

The other source of assistance is this. It has been found that each

of the great groups thus obtained is characterised also by the presence of certain fragments of animals and plants of a kind peculiar to itself. This limitation of particular species of fossils to particular groups of rock has been found to be so precise and so invariable, that it might be trusted to independently of any local proof of the order of superposition of the beds,or of the nature of the material of which they were composed. If therefore all we could see in any locality was a single bed of rock, we should know from the species of the fossils which it contained, to which of the great groups mentioned above it belonged, and what groups of rock we might expect to find below it.

There has, in fact, been a succession of races of animals and plants living on the globe, their creation and extinction having been regulated by certain laws; the species having been created in a regular order, and no species once extinct having ever been re-created.

When once the order of the existence of the different species of fossils is known, therefore, they evidently form a chronological series or table of dates, just as coins do in human history, with this advantage over coins, that nature makes no false money, and never impresses a spurious dye upon her workmanship.

The main results of the reading of this history may be stated as follows :

The antiquity of the Earth, as a globe such as it now is its surface diversified as now with land and water, seas, continents, and islands-is so vast as to be illimitable. The atmosphere, with its winds, and clouds, and rains; the sea, with its waves, and tides, and currents, are the same now as in the earliest geological periods. The land only has shifted its place--not once only, but many times,

-in obedience to the action of those slowly moving causes which are now at work upon it in our own time, to make it change its place once more.

The species of animals and plants that now inhabit the Earth have come into existence, slowly and gradually, one after another, according as room was made for them, or their presence was required by the extinction of species that had gone before.

There was a period in the history of the Earth when not one of the present animals and plants were living, though we know the waters teemed with animals as they do now, because we have preserved for us the hard parts and coverings of hundreds of the creatures of those days. At a later period, a few of the now-living animals existed, together with many now extinct; while in newer and yet newer deposits, the proportion of living, to extinct species becomes gradually greater, till they are at length

universal. If we go back to the rocks where all are extinct, we still find the same law of gradual progression, of gradual creation, and gradual extinction to prevail. Some forms are confined to a few beds, or, perhaps, to one single bed; others range through many. Some species or genera come in gradually, being at first rare, afterwards abundant, then rare again, and finally extinct. Some come in at once, as it were at a maximum, and disappear as suddenly.

The periods of the existence of different species generally overlap each other, so as to form an endless and unbroken chain of creations and deaths. There have been no sudden and general catastrophes by which entire populations have been at once destroyed over the whole Earth-a clean sweep made, and an entirely new creation brought into being.

Wherever we have the appearance of these sudden breaks, we can always trace it to the fact of vast intervals of time having elapsed, during which no deposition of beds of rock took place in the district under examination, or during which beds of rock once formed have been destroyed and washed away.

From the earliest geological period down to the present hour at which we write, the physical forces of water and of fire have been for ever at work upon the Earth, just as they are now at work upon it ;-one unbroken chain of animal and vegetable life has inhabited the Earth, gradually and stealthily coming into existence, slowly and gradually disappearing just as now animals and vegetables are gradually exterminated-just as now new species may be, from time to time, first placed upon the Earth.*

Such being the truths taught us by Geology, the question naturally arises, how are they to be reconciled with the literal interpretation of the account of the Creation given to us in the first chapter of Genesis? Our own answer to that question would be that of the Reve