GEOLOGICAL ILLUSTRATIONS, (continued 2)

It has been said, and it is even a matter of general belief among mariners, say MM. Quoy and Gaimard, that there occur in the equatorial seas shoals composed of corals, which rise from the greatest depths, like walls at the bottom of which the sounding line finds no ground. The fact certainly does exist in so far as regards the depth spoken of; and it is this very circumstance which is productive of so much danger to vessels, which, when taken in a calm and carried away by currents, cannot cast anchor in such places. But it is not correct to say that these reefs are entirety formed of madrepores. First, because the species which always form the most considerable banks, such as some meandrinæ, certain caryophylleæ, but especially the astreæ, adorned with the most beautiful and velvety colours, require the influence of light to perfect them; because they are not seen to grow beyond a few yards of depth; and because they cannot consequently be developed at a depth of ten or twelve hundred feet, as they would necessarily be, did they raise the cliffs in question. Besides, these different species of animals would then almost exclusively enjoy the privilege of living at all depths, under all degrees of pressure, and, so to speak, in all temperatures.

Another circumstance to which navigators have not adverted, which corroborates the opinion here stated, is, that, in depths so great as those to which we allude, the sea, always agitated at the surface, breaks with force upon these reefs, without requiring for that purpose any additional impulse from the winds. And by merely attending to the necessary consequences of the observations of these same navigators, who say (what is very true) that, wherever the waves are agitated, the lithophytes are unable to go on with their work, because they destroy their frail edifices, we shall acquire the moral certainty that these submarine steeps are not produced by these animalcules. But, in these same places, let there occur a hollow, a sheltered spot of some kind, and then they will immediately raise their habitations, and will contribute to diminish the little depth that already exists there. And this is what may be seen in almost all the places where an elevated temperature permits these animals to grow in abundance.

In the localities where the tides are sensible, their currents alone may sometimes form irregular canals between the madrepores, without their ever being encumbered with their species, from the twofold cause united, of the motion and the coldness of the water; while, on the other hand, the flexible alcyonia are seen to multiply there.

When these geological dispositions are carefully observed, we see that the zoophytes rise to the surface of the waves, never beyond it; after which the generation which has attained thus far appears to die. It is destroyed much sooner, if, from the effect of the tides, these frail animalcules are exposed naked to the action of a burning sun. When there occur small hollows in these heaps of inert spoils, deprived of their inhabitants, which are always covered by the water, several tufts of those lithophytes are still remarked, which, having escaped from the almost general destruction, glow with the most lively colours. Then, the families which are developed anew, not being able to build on the outside of those reefs on which the sea is constantly breaking, draw nearer and nearer the shore, where the waves now deadened have scarcely any more action upon them, as in the Isle of France, at Timor, the Papua, the Marian, and the Sandwich Islands; provided always the waters had not a great depth, as is the case at Turtle Island, of which Cook speaks, where no bottom is found between the madrepore reefs and the island, notwithstanding the shortness of the space which exists between these two points.

If we examine these animals in the places best adapted to their growth, we shall see their different species, the forms of which, as varied as they are elegant, become rounded into balls, spread out into fans, or ramify into trees, mingling together, blending with each other, and reflecting the varied hues of red, yellow, blue and violet.

It is well known that all these alleged walls, exclusively formed of corals, are intersected with openings through which the sea enters and retires with violence; and every body knows the danger which Captain Cook ran on one occasion, on the coast of New Holland, when he had no other resource, in order to save himself from destruction, than to take the sudden resolution of attempting one of these narrow passes, where one is always sure of finding plenty of water. And this circumstance also comes in support of what we have advanced; for, if these perpendicular walls were entirely composed of madrepores, they would present no deep openings in their continuity, because it is the property of zoophytes to build in masses that have no interruption; and because, again, could they raise themselves from very great depths, they would end with encumbering and shutting up these passages; a circumstance which does not take place, and probably never will, from the causes which we have related.

If these facts prove, that madrepores cannot exist at very great depths, the submarine rocks, which they only increase in height, are not, therefore, exclusively formed by them.

We now come to the second part of the argument; and we assert, that there are no islands of any magnitude and constantly inhabited by man, that are formed by corals; and that the layers which they construct under the water, are not more than a few fathoms in thickness.

We shall commence with the second part of this question. The impossibility of penetrating to the bottom of the sea to examine at what precise depth the solid zoophytes establish themselves, constrains us to confine ourselves to what has taken place in former times; and the monuments which the ancient revolutions of the globe have disclosed to our view, will serve to prove what is going on in our own days. We shall mention what has been seen in several places, and we shall first speak of the island which Peron took for the theatre of the great works of these polypi, namely the island of Timor.

The banks of coral which the sea has left exposed in the land, as it retired, are remarkable for their uncommon magnitude. The whole shores of Coupang are formed of them, and the low hills in its vicinity are enveloped in them; but a few hundred yards from the town, they disappear, when distinct strata of slate make their appearance. The corals form a bed over the subjacent rocks from 25 to 80 feet thick.

Every thing announces that, in the Island of Timor, there exist no mountains exclusively formed of corals. As in all extensive countries, they are composed of various substances. Quoy and Gaimard having coasted it for about fifty leagues, sufficiently near to enable them to form an idea of its geography, were able to see that it exhibited volcanic appearances in several parts. Besides it abounds in mines of gold and copper, which, in conjunction with what we have already mentioned, shews in a general way the nature of the rocks of which it is composed.

Perhaps, remarks Quoy and Gaimard, the Bald-Head, a mountain of King George’s harbour in New Holland, which Vancouver has described in passing, and on the summit of which he saw perfectly preserved branches of coral, might be adduced as a fact in opposition to the opinion here advanced. Yet the phenomenon exhibited there, is still precisely the same as at Timor, and in a thousand other places[382]. The zoophytes have built upon a basis previously existing, and they occupy only the surface of it. For why should this Bald-Head differ from Mount Gardner, which, although close by it, is formed of primitive rocks? Besides, Peron says, that it has the same geological constitution. (T. ii. p. 133.)

At Rota, one of the Marian Isles, M. Gaudichaud, detached from the limestone rock, at about a hundred toises above the level of the sea, branches of true madrepores, in perfect preservation. Here are, then, three localities in which they are found at great heights. We have observed them, say the French naturalists, at infinitely lower elevations in several other places, as at the Isle of France, where they form a bed more than six feet thick, between two streams of lava; at Wahou, one of the Sandwich Islands, where they have not a greater elevation, but extend for several hundred toises over the surface of the island. In all these cases, it is necessary to distinguish between the lithophytes, which have, by their living powers, formed continuous masses, from those which, after having been rolled about, broken down by the water, and mixed with sea shells, contribute to form those deposits known by the name of madrepore limestone. The latter sort is nothing but the debris of the former. Deposits of this description occur in the Marian Isles, and in those of the Papous; they occur also on the coasts of France, and in several other places.

It would appear from observations made in Timor and other places, that the species of the genus Astræa which are the only ones capable of covering immense extents of surface, do not commence their operations at a greater depth than twenty-five or thirty feet, in order to raise their habitations to near the surface of the sea. Fragments of these species are never obtained, either with the sounding line, or upon the anchors; nor do we ever see them, unless in places where the water is shallow; while the branched madrepores, which do not form thick and continuous beds, either on the elevated places which the ocean has left, or on the shores where they still exist, live at considerable depths.

It is evident, then, that these corals have erected their fabrics on the summits of submarine hills and mountains; and that all those reefs of Taiti, the Dangerous Archipelago, Navigators’ Islands, the Friendly Islands, &c. are composed of madrepores only at the surface.

We thus consider it demonstrated, that the rocks of the solid zoophytes or coral, are not capable of forming the immense bases on which the greater number of the islands that occur in the Pacific Ocean rest.

There now remains for us to state how these animals, by their union, are capable of raising small islets. Forster, as already stated, has given a very good description of the manner in which this is effected. In fact, when these animalcules have raised their habitations to the surface of the water, under the shelter of the land, and they remain uncovered during the reflux of the tide, the hurricanes which sometimes supervene, by the agitation which they produce in those shallow waters, throw up from the bottom sand and mud. These substances are detained in the sinuosities and cavities formed between the corals, and thus serve to fix them together, and connect them into masses. Whenever the summit of this new island can remain constantly uncovered by the sea, and the waves can no longer destroy what they themselves have contributed to form, then its extent is enlarged, and its edges are gradually raised by the successive addition of sand. According to the direction of the winds and currents they may long remain sterile; but if the seeds of vegetables be transported to them from the neighbouring shores, by the action of these two causes, then, in latitudes favourable to their development, we presently see these islands becoming covered with verdure, the successively accumulated remains of which form layers of soil, which contribute to the elevation of the surface.

But, in order that this phenomenon of growth be accomplished, the distance from land must not be too great, because then the vegetables cannot get so easily to the islets in question, which then remain almost always bare and sterile. And for this reason what navigators report of those madrepore Islands of the Great Ocean, which are covered with verdure, and are yet at a great distance from any known land, has always appeared to us extraordinary; and that so much the more, that, in those vast spaces, the violence of the waves, which nothing can break there, must disturb the operations of the zoophytes. We do not, however, deny the existence of these islands, which it would be interesting carefully to examine anew; for, whenever navigators meet with low islands between the Tropics, they do not hesitate, in compliance with the generally received opinion, to say that they consist of madrepores. Yet how many islands, which scarcely rise above the surface of the water, recognise no such origin? We may mention, as an example, the Island of Boni, situated under the equator, the beautiful vegetation of which rises upon limestone. Cocoa Island, near Guam, is in the same condition, being also composed of limestone. In general, if they are inhabited, consequently they have springs or lakes of fresh water, we may almost be certain that they are not composed of lithophytes, or are only so in part, because springs could not be formed in their porous substances. Some of the Caroline Isles are excessively low; we supposed them encrusted with madrepores; and as they have inhabitants there must be somewhere in them a soil favourable to the accumulation of fresh water[383].

In restraining the power of these animalcules, concludes Quoy and Gaimard, and in pointing out the limits which nature has prescribed them, we have no other object than to furnish more correct data to the naturalists who aspire to great hypothetical considerations, regarding the conformation of the globe. On reconsidering these zoophytes with greater attention, they will no longer be seen filling up the basins of the seas, raising islands, increasing the size of the continents, threatening future generations with a solid equatorial circle formed of their spoils. Their influence, with regard to the road-steads or harbours, in which they multiply, is already great enough, without adding more to it. But, compared with the masses on which they rest, what are their layers, often interrupted, and which must be searched for with care, before they can be recognised, to the enormous volcanic peaks of the Sandwich Islands, the Island of Bourbon, the Moluccas, the Marian Islands, the mountains of Timor, New Guinea, &c. &c.? Nothing, certainly; and the solid zoophytes are in no degree capable of being compared with the testaceous mollusca, with reference to the materials which they have furnished, and still continue to furnish to the crust of the Globe.

ON THE LEVEL OF THE BALTIC.

About the middle of the last century, a controversy took place among the natural philosophers of the north of Europe, regarding the alleged gradual lowering of the level of the sea in general, and of the Baltic Sea in particular. Celsius was the first who introduced this idea to notice. He generalised it by applying it to all the planets, and was supported by the authority of the celebrated Linnæus. He soon perceived, however, that the point could never be settled by mere discussion, and that facts alone could lead to any certain result. Observation was therefore had recourse to; and thus the dispute in question had at least one good effect, that of directing to the subject the attention of men of science, whose situation might enable them to mark the variations of level that take place along the coasts of the North Sea. The results of investigations undertaken for this purpose, are now beginning to be collected.

In the course of 1820 and 1821, Mr Bruncrona, assisted by the officers of the Pilotage Establishment, and other qualified persons, undertook the examination of all the authentic measures that had been established upon the west coast of the Baltic, during the last half century. The results of this examination are given in a short memoir, inserted in the Swedish Transactions for 1823. The following table indicates the degree to which the level of the sea has fallen during the last forty years, on the coast of Sweden, at various latitudes. It is proper to remark, that, in some of the places observed, the measures were much older, and in some others much more recent, than the period of forty years. In both these cases, the change of level that must have been effected during this period, has been estimated, by calculating the mean annual depression furnished by the observations.

Latitude. Fall of surface in forty years. Latitude. Fall of surface in forty years. Latitude. Fall of surface in forty years.

East Coast. Feet. East Coast. Feet. East Coast. Feet.

63° 59′ 1.50 59° 17′ 2.17 56° 10′ 0.00

... ... 2.50 58 44 1.00 56 11 0.00

... ... 0.50 58 42 1.08 55 53 0.00

61 43 2.50 58 45 1.17

61 37 2.83 58 35 2.00 South-West Coast.

61 32 2.50 58 28 0.07 55 23 0.00

61 45 2.50 58 11 0.83 55 22 0.00

60 11 2.33 58 8 1.00 57 21 0.00

59 46 0.17 57 50 1.00 57 53 1.00

59 46 2.00 56 41 0.41

Of the facts collected in the course of this investigation, the following may be mentioned as tending to support the opinion of a fall of level.

1st, It is generally believed among the pilots of the Baltic, that the sea has become shallower along the course which vessels ordinarily follow; but, it is added, that this alteration is more sensible in the places where the tide collects sand, detached pebbles, and sea-weeds, or in those where the bottom is composed of rocks. The same observation has been made in the neighbourhood of some large towns and fisheries; for example, a hydrographic chart made in 1771, gives six fathoms for the mean depth of the sea opposite the harbour of Landskrona, whereas, in 1817, the sounding line scarcely gave five fathoms at the same point.

2d, According to the oldest and most experienced pilots, the straits which separate the numerous islets scattered along the coast of Sweden, from Haarparanda to the frontiers of Norway, received vessels that drew ten feet of water; now they are not practicable for boats that draw more than two or three feet.

3d, The pilots further affirm, that, along the whole coast of Bahusia, the bottom undergoes a diminution, which becomes sensible every ten years in certain places, where it is composed of rocks. Several other parts of the Baltic may be cited, in which a similar change has been remarked.

M. C. P. Hallstrom, in an Appendix to Mr Bruncrona’s Memoir, gives the following table of the diminution observed in the depth of the waters of the Gulf of Bothnia.

Places. Mean marked in Height of the water reobserved in Fall beneath the original mark in feet. Number of years. Fall of the water in 100 years, in feet.

Raholem, parish of Lower Kalix, 1700 1750 2.05 50 4.10

1775 2.49 75 4.32

Stor Rebben, parish of Pitea, 1751 1785 1.70 34 5.00

1796 1.90 45 4.22

Ratan, parish of Bygdea, 1749 1785 2.70 36 4.72

1795 2.50 46 5.43

1819 2.60 70 3.47

1774 1785 0.55 11 5.00

1795 1.16 21 5.52

1819 1.60 45 3.57

1795 1819 0.65 24 2.71

Rönnskat, on the coast of Wasa, 1755 1797 1.70 42 4.05

1821 2.87 65 4.35

Wargön, on the coast of Wasa, 1755 1785 1.45 30 4.83

1797 1.69 42 4.02

1821 2.87 65 4.35

Lögfrundet, near Sefle, 1731 1785 2.90 54 5.37

1796 2.17 65 3.34

Ulfon, in Angermanland, 1795 1822 1.58 27 5.85

It is not demonstrated that the numbers of the last column represent exactly the lowering of the water in a century; for it has not yet been sufficiently determined if this lowering be uniform, or if it vary at different periods, and if it depend upon some local circumstance,—upon the climate,—or upon the state of the atmosphere. Nor is it properly established, that this lowering, which becomes less perceptible from the north of the Baltic, until it disappears entirely at the southern extremity, follows precisely the same law of diminution as the latitude. It appears to be uniform in the whole extent of the Gulf of Bothnia, and it rises about four feet and a quarter in that region; at Calmar (lat. 57° 50′) it is only two feet; but it is not yet known whether it decreases in a regular manner between these two places.

Some authors consider the facts related by MM. Bruncrona and Halstrom, as deciding the question in favour of those who believe in a lowering of the level of the Baltic. The editor of the Annalen der Physik[384] goes farther, and seems to consider it as confirming the opinion of a general lowering of the level of the sea. In support of this opinion, he adduces the traditions and observations of the natives of Otaheite and of the Moluccas and Sunda Islands, regarding the retreat of the sea in several parts of their coast. We are disposed to stand neutral in this matter. The geographers who have collected the greatest number of facts relating to the level of the inland seas, and of the ocean in its various regions, find nearly as many in favour of a rise as in favour of a fall of level. The very distribution of contrary indications, leads them to believe in a partial displacement of the mass of waters from one region towards another, and even from the one side of an inland sea towards the opposite side; a displacement which might be owing to fugitive or more or less durable causes, such as a variation of temperature in the polar regions, the action of winds and of currents, modified by the greater or less quantity of water in the rivers that feed the different basins, upon the sides opposed to their direction.

Are the facts contained in the memoir in question of a nature to overthrow this opinion? They do not appear so to us. The two series of observations which are adduced, only shew a fall upon the coasts of Sweden, properly so called, that is to say, upon the west coast of the Baltic, and the east coast of the Cattegat. Two observations only have been made upon the coasts of Finland, toward the extremity of the Gulf of Bothnia. These facts would perfectly accord with the opinion of those who think that the currents determined from the north to the south of the Baltic by the numerous streams which rush into it, push the waters toward the south shore, that of Pomerania, Mecklenbourg, and Holstein; and that the waters consequently gain upon the land on this coast, as numerous historical facts attest, while they retire along the northern shores, those of the Gulf of Bothnia. Be this as it may, the question as to the constancy of the level of the sea cannot be considered as decided, until a long series of observations shall have been made upon authentic and perfectly fixed measures erected upon all the shores of the different seas, and of the different regions of the ocean. Those which have been published in the Swedish Transactions furnish important documents for this purpose; and similar ones should be begun to be collected in other countries.

The phenomena exhibited by the waters of the Baltic engaged the attention of two rival speculators, Playfair and Deluc; and their views are often alluded to by geologists. We shall here state them in their own words. Professor Playfair, in his well known and elegant work on the Huttonian Theory of the Earth, has the following remarks:

“If we proceed further to the north, to the shores of the Baltic for instance, we have undoubted evidence of a change of level in the same direction as on our own shores. The level of the sea has been represented as lowering at so great a rate as forty inches in a century. Celsius observed, that several rocks which are now above the water, were not long ago sunken rocks, and dangerous to navigators; and he took particular notice of one which, in the year 1680, was on the surface of the water, and, in the year 1731, was 20½ Swedish inches above it. From an inscription near Aspo, in the lake Melar, which communicates with the Baltic, engraved, as is supposed, about five centuries ago, the level of the sea appears to have sunk in that time no less than thirteen Swedish feet. All these facts, with many more which it is unnecessary to enumerate, make the gradual depression, not only of the Baltic, but of the whole Northern Ocean, a matter of certainty.”—Playfair’s Illustrations, p. 445.

That indefatigable and accurate observer De Luc, has the following commentary on the preceding passage.

“It would be unnecessary to mention even the two inconsiderable facts above, if the depression of the level of the seas were indeed a matter of certainty; for the best authenticated and the least equivocal monuments of their change would then abound along all their coasts. But proofs are every where found that such a change is chimerical: they may be seen in all the vales coming down to these seas, in which there is no perceptible impression of the action of any waters but those of the land, and no vestige, through their whole extent, of any permanent abode of those of the sea; and proofs to the same effect are equally visible, along the coasts of both these seas, in all the new lands which have been formed on them, and which, being perfectly horizontal from the point where their formation commenced, evidently show that the water displaced by them has been constantly at the same level. Hence appears the necessity of multiplying, as I have done, and shall continue to do, for the subversion of a prejudice of such ancient date, the examples of these peremptory proofs of its total want of foundation. The rock mentioned by Celsius had probably been observed by him at times when the level of the sea was different; its known differences much exceeding the quantity here specified. As for the inscription near Aspo, in a country abounding with lakes as much as that which I have above described, if we are acquainted with its terms, we should probably find it to be, like many which I have seen in various places along the course of the Oder and the Elbe, the monument of some extraordinary inundation of the land, from the sudden melting of the snows in the mountains, at a time when the water had been prevented from running off by an equally extraordinary rise of the level of the sea; of which the effects on low coasts may extend very far inland.

“By this conclusion, however, from these few facts, contrary to every thing observed on the coasts of this sea, Mr Playfair thinks himself authorised to maintain, that the gradual depression, not only of the Baltic, but of the whole northern ocean, is a matter of certainty; afterwards he examines merely which of these two causes, the subsidence of the sea itself, or the elevation of the land around it, agrees the best with the phenomena; and he decides in favour of the latter, pointing out its accordance with the Huttonian Theory.”

FOSSIL REMAINS OF THE HUMAN SPECIES.

From the observations of Werner and others, it appears, that the most simple animals are those first met with in a mineralized state; that these are succeeded by others more perfect, and which are contained in newer formations; and that the most perfect, as quadrupeds, occur only in the newest formation. But we naturally inquire, have no remains of the human species been hitherto discovered in any of the formations? Judging from the arrangement already mentioned, we would naturally expect to meet with remains of man in the newest of the formations. In the writings of ancient authors there are descriptions of anthropolithi. In the year 1577, Fel. Plater, Professor of Anatomy at Basle, described several fossil bones of the elephant found at Lucerne, as those of a giant at least nineteen feet high. The Lucernese were so perfectly satisfied with this discovery, that they caused a painting to be made of the giant, as he must have appeared when alive, assumed two such giants as the supporters of the city arms, and had the painting hung in their public hall. The Landvoigt Engel, not satisfied with this account of these remains, maintained that our planet, before the creation of the present race of men, was inhabited by fallen angels, and that these bones were part of the skeletons of some of those miserable beings. Scheuchzer published an engraving and description of a fossil human skeleton, which proved to be a gigantic species of salamander or proteus. Spallanzani describes a hill of fossil human bones in the island of Cerigo; but this also is an error, as has been satisfactorily shewn by Blumenbach. Lately, however, a fossil human skeleton has been imported into this country from Guadaloupe, by Sir Alexander Cochrane. It is imbedded in a block of calcareous stone, composed of particles of limestone and coral, and which, like the aggregations of shells found on the limestone coasts in some parts of this country, has acquired a great degree of hardness. It is therefore an instance of a fossil human petrifaction in an alluvial formation. The engraving here given is copied from the Philosophical Transactions of the Royal Society of London; and the following description of the fossil remains it exhibits is that of Mr Konig, which has been drawn up with great care.

“The situation of the skeleton in the block was so superficial, that its presence in the rock on the coast had probably been indicated by the projection of some of the more elevated parts of the left fore-arm.

“The operation of laying the bones open to view, and of reducing the superfluous length of the block at its extremities, being performed with all the care which its excessive hardness, and the relative softness of the bones, required, the skeleton exhibited itself in the manner represented in the annexed drawing (Pl. I.) with which my friend Mr Alexander has been so good as to illustrate this description.

“The skull is wanting; a circumstance which is the more to be regretted, as this characteristic part might possibly have thrown some light on the subject under consideration, or would, at least, have settled the question, whether the skeleton is that of a Carib, who used to give the frontal bone of the head a particular shape by compression, which had the effect of depressing the upper and protruding the lower edge of the orbits, so as to make the direction of their opening nearly upwards, or horizontal, instead of vertical[385].

“The vertebræ of the neck were lost with the head. The bones of the thorax bear all the marks of considerable concussion, and are completely dislocated. The seven true ribs of the left side, though their heads are not in connexion with the vertebræ, are complete; but only three of the false ribs are observable. On the right side only fragments of these bones are seen; but the upper part of the seven true ribs of this side are found on the left, and might at first sight be taken for the termination of the left ribs; as may be seen in the drawing. The right ribs must therefore have been violently broken and carried over to the left side, where, if this mode of viewing the subject be correct, the sternum must likewise lie concealed below the termination of the ribs. The small bone dependent above the upper ribs of the left side, appears to be the right clavicle. The right os humeri is lost; of the left nothing remains except the condyles in connexion with the fore-arm, which is in the state of pronation; the radius of this side exists nearly in its full length, while of the ulna the lower part only remains, which is considerably pushed upwards. Of the two bones of the right fore-arm, the inferior terminations are seen. Both the rows of the bones of the wrists are lost, but the whole metacarpus of the left hand is displayed, together with part of the bones of the fingers: the first joint of the fore-finger rests on the upper ridge of the os pubis; the two others, detached from their metacarpal bones, are propelled downwards, and situated at the inner side of the femur, and below the foramen magnum ischii of this side. Vestiges of three of the fingers of the right hand are likewise visible, considerably below the lower portion of the fore-arm, and close to the upper extremity of the femur. The vertebræ may be traced along the whole length of the column, but are in no part of it well defined. Of the os sacrum, the superior portion only is distinct: it is disunited from the last vertebra and the ilium, and driven upwards. The left os ilium is nearly complete, but shattered, and one of the fragments depressed below the level of the rest; the ossa pubis, though well defined, are gradually lost in the mass of the stone. On the right side, the os innominatum is completely shattered, and the fragments are sunk: but towards the acetabulum, part of its internal cellular structure is discernible.

“The thigh-bones, and the bones of the leg of the right side, are in good preservation, but being considerably turned outwards, the fibula lies buried in the stone, and is not seen. The lower part of the femur of this side is indicated only by a bony outline, and appears to have been distended by the compact limestone that fills the cavities both of the bones of the leg and thigh, and to the expansion of which, these bones probably owe their present shattered condition. The lower end of the left thigh-bone appears to have been broken and lost in the operation of detaching the block; the two bones of the leg, however, on this side, are nearly complete; the tibia was split almost the whole of its length a little below the external edge, and the fissure being filled up with limestone, now presents itself as a dark-coloured straight line. The portion of the stone which contained part of the bones of the tarsus and metatarsus, was unfortunately broken; but the separate fragments are preserved.

“The whole of the bones, when first laid bare, had a mouldering appearance, and the hard surrounding stone could not be detached without frequently injuring their surface; but after an exposure for some days to the air, they acquired a considerable degree of hardness. Sir H. Davy, who subjected a small portion of them to chemical analysis, found that they contained part of their animal matter, and all their phosphate of lime.”

Account of the Displacement of that part of the Coast of the Adriatic which is occupied by the Mouths of the Po.

That portion of the shore of the Adriatic which lies between the lake, or rather lagune, of Commachio, and the lagunes of Venice, has undergone considerable alterations since ancient times, as is attested by authors worthy of entire credit, and as is still evinced by the actual state of the soil in the districts near the coast; but it is impossible now to give any exact detail of the successive progress of these changes, and more especially of their precise measures during the ages which preceded the twelfth century of our era.

We are, however, certain, that the city of Hatria, now called Adria, was formerly situated on the edge of the coast; and by this we attain a known fixed point upon the primitive shore, whence the nearest part of the present coast, at the mouth of the Adige, is at the distance of 25,000 metres[386]; and it will be seen in the sequel, that the extreme point of the alluvial promontory formed by the Po, is farther advanced into the sea than the mouth of the Adige by nearly 10,000 metres[387].

The inhabitants of Adria have formed exaggerated pretensions, in many respects, as to the high antiquity of their city, though it is undeniably one of the most ancient in Italy, as it gave name to the sea which once washed its walls. By some researches made in its interior and its environs, a stratum of earth has been found mixed with fragments of Etruscan pottery, and with nothing whatever of Roman manufacture. Etruscan and Roman pottery are found mixed together in a superior bed, on the top of which the vestiges of a theatre have been discovered. Both of these beds are far below the level of the present soil. I have seen at Adria very curious collections, in which these remains of antiquity are separately classed; and having, some years ago, observed to the viceroy, that it would be of great importance, both to history and geology, to make a thorough search into these buried remains at Adria, carefully noticing the levels in comparison with the sea, both of the primitive soil, and of the successive alluvial beds, his Highness entered warmly into my ideas; but I know not whether these propositions have been since carried into effect.

Following the coast, after leaving Hatria, which was situated at the bottom of a small bay or gulf, we find to the south a branch of the Athesis or Adige, and of the Fossa Philistina, of which the remaining trace corresponds to what might have been the Mincio and Tartaro united, if the Po had still run to the south of Ferrara. We next find the Delta Venetum, which seems to have occupied the place where the lake or lagune of Commachio is now situated. This delta was traversed by seven branches of the Eridanus or Po, formerly called also the Vadis Padus or Podincus; which river, at the diramification of these seven branches, and upon its left or northern bank, had a city named Trigoboli, whose site could not be far from where Ferrara now stands. Seven lakes, inclosed within this delta, were called Septem Maria, and Hatria was sometimes denominated Urbs Septem Marium, or the city of the seven seas or lakes.

Following the coast from Hatria to the northwards, we come to the principal mouth of the Athesis or Adige, formerly named Fossa Philistina, and afterwards Estuarium Altini, an interior sea, separated by a range of small islands from the Adriatic Gulf, in the middle of which was a cluster of other small isles, called Rialtum, and upon this archipelago the city of Venice is now seated. The Estuarium Altini is what is now called the Lagune of Venice, and no longer communicates with the sea, except by five passages, the small islands of the Archipelago having been united into a continuous dike.

To the east of the lagunes, and north from the city of Este, we find the Euganian mountains, or hills, forming, in the midst of a vast alluvial plain, a remarkable isolated group of rounded hills, near which spot the fable of the ancients supposes the fall of Phæton to have taken place. Some writers have supposed that this fable may have originated from the fall of some vast masses of inflamed matters near the mouths of the Eridanus, that had been thrown up by a volcanic explosion; and it is certain that abundance of volcanic products are found in the neighbourhood of Padua and Verona.

The most ancient notices that I have been able to procure respecting the situation of the shores of the Adriatic at the mouths of the Po, only begin to be precise in the twelfth century. At that epoch the whole waters of this river flowed to the south of Ferrara, in the Po de Volano and the Po di Primaro, branches which inclosed the space occupied by the lagune of Commachio. The two branches which were next formed by an irruption of the waters of the Po to the north of Ferraro, were named the river of Corbola, Longola, or Mazzorno, and the river Toi. The former, and more northern of these, received the Tartaro, or canal bianco, near the sea, and the latter was joined at Ariano by another branch derived from the Po, called the Goro river. The sea-coast was evidently directed from south to north, at the distance of ten or eleven thousand metres[388] from the meridian of Adria; and Loreo, to the north of Mesola, was only about 2000 metres[389] from the coast.

Towards the middle of the twelfth century, the flood-waters of the Po were retained on their left or northern side by dikes near the small city of Ficarolo, which is about 19,000 metres[390] to the north-west of Ferrara, spreading themselves southwards over the northern part of the territory of Ferrara and the Polesine of Rovigo, and flowed through the two formerly mentioned canals of Mazzorno and Toi. It seems perfectly ascertained, that this change in the direction of the waters of the Po had been produced by the effects of human labours; and the historians who have recorded this remarkable fact only differ from each other in some of the more minute details. The tendency of the river to flow in the new channels, which had been opened for the more ready discharge of its waters when in flood, continually increased; owing to which the two ancient chief branches, the Volano and Primaro, rapidly decreased, and were reduced in less than a century to their present comparatively insignificant size; while the main direction of the river was established between the mouth of the Adige to the north, and what is now called Porto di Goro, on the south. The two before-mentioned canals of Mazzorno and Toi becoming insufficient for the discharge, others were dug; and the principal mouth, called Bocco Tramontana, or the northern mouth, having approached the mouth of the Adige, the Venetians became alarmed in 1604; when they excavated a new canal of discharge, named Taglio de Porto Viro, or Po delle Fornaci, by which means the Bocco Maestra, was diverted from the Adige towards the south.

During four centuries, from the end of the twelfth to that of the sixteenth, the alluvial formations of the Po gained considerably upon the sea. The northern mouth, which had usurped the situation of the Mazzorno canal, becoming the Rama di Trimontana, had advanced in 1600 to the distance of 20,000 metres[391] from the meridian of Adria; and the southern mouth, which had taken possession of the canal of Toi, was then 17,000 metres[392] advanced beyond the same point. Thus the shore had become extended nine or ten thousand metres[393] to the north, and six or seven thousand to the south[394]. Between these two mouths there was formerly a bay, or a part of the coast less advanced than the rest, called Sacca di Goro. During the same period of four hundred years previous to the commencement of the seventeenth century, the great and extensive embankments of the Po were constructed; and also, during the same period, the southern slopes of the Alps began to be cleared and cultivated.

The great canal, denominated Taglio di Porto Viro, or Po delle Fornaci, ascertains the advance of the alluvial depositions in the vast promontory now formed by the mouths or delta of the Po. In proportion as their entrances into the sea extend from the original land, the yearly quantity of alluvial depositions increases in an alarming degree, owing to the diminished slope of the streams, which was a necessary consequence, of the prolongation of their bed, to the confinement of the waters between dikes, and to the facility with which the increased cultivation of the ground enabled the mountain torrents which flowed into them to carry away the soil. Owing to these causes, the bay called Sacra di Goro was very soon filled up, and the two promontories which had been formed by the two former principal mouths of Mazzorno and Toi, were united into one vast projecting cape, the most advanced point of which is now 32,000 or 33,000 metres[395] beyond the meridian of Adria: so that in the course of two hundred years, the mouths or delta of the Po have gained about 14,000 metres[396] upon the sea.

From all these facts, of which I have given a brief enumeration, the following results are clearly established.

First, That, at some ancient period, the precise date of which cannot be now ascertained, the waves of the Adriatic washed the walls of Adria.

Secondly, That, in the twelfth century, before a passage had been opened for the waters of the Po at Ficarrolo; on its left or northern bank, the shore had been already removed to the distance of nine or ten thousand metres[397] from Adria.

Thirdly, That the extremities of the promontories formed by the two principal branches of the Po, before the excavation of the Taglio di Porto Viro, had extended, by the year 1600, or in four hundred years, to a medium distance of 18,500 metres[398] beyond Adria; giving, from the year 1200, an average yearly increase of the alluvial land of 25 metres[399].

Fourthly, That the extreme point of the present single promontory, formed by the alluvions of the existing branches, is advanced to between thirty-two and thirty-three thousand metres[400] beyond Adria; whence the average yearly progress is about seventy metres[401] during the last two hundred years, being a greatly more rapid proportion than in former times.

Prony.

Note, p. 244.

On the Universal Deluge.

Mr Cuvier in the present work, and more recently in a note to Mr Lemaire’s edition of Ovid’s Metamorphoses, enumerates the Mosaic, Grecian, Assyrian, Persian, Indian, and Chinese traditions, concerning a universal deluge; and concludes from them, that the surface of the globe, five or six thousand years ago, underwent a general and sudden revolution, by which the lands inhabited by the human beings who lived at that time, and by the various species of animals known at the present day, were overflowed by the ocean; out of which emerged the present habitable portions of the globe. This celebrated naturalist maintains, that these regions of the earth were peopled by the few individuals who were preserved, and that the tradition of the catastrophe has been preserved among these new races of people, variously modified by the difference of their situation and their social disposition. According to Mr Cuvier, similar revolutions of nature had taken place, at periods long antecedent to that of the Mosaic deluge. The dry land was inhabited, if not by human beings, at least by land animals at an earlier period; and must have been changed from the dry land to the bed of the ocean; and it might even be concluded from the various species of animals contained in it, that this change, as well as its opposite, had occurred more than once.

This opinion being brought forward in a geognostic work, especially in a work abounding in such valuable matters of fact, and stated as the result of geognostic investigation, we may be permitted, in this point of view, to examine it; and to ask, whether, from the phenomena exhibited by the present condition of the earth’s surface, we are entitled to conclude that it owes its conformation to such a universal deluge.

We know, from arguments suggested by chemistry and the higher mechanics, that the globe was once in a state of fluidity; hence it might be maintained with some appearance of probability, that the condition of the earth, previous to the existence of organic matter, depended upon fusion; and that the primitive rocks are of igneous origin. Since, however, granite has been found above rocks of various kinds which contain the remains of organic bodies, we are under no necessity of ascribing to primitive rocks an origin different from that of subsequent formations; and, without having recourse to other arguments, the fact, that aquatic animals are the most abundant of fossil organic remains from the earliest of the transition to the latest of the secondary and tertiary formations, affords evidence that they are precipitates from water.

Notwithstanding the great and daily advancement of science, our knowledge of chemistry is still too imperfect for us to arrive at an adequate knowledge of the state of this water, or rather sea, as, from its universal expansion, it must be denominated. Did it contain dissolved in it at the same time all the materials from which the various beds of rock were formed; what were the solvents of those materials which we find, either insoluble in water, or at least not easily soluble; by what means were the precipitates produced; and whence came this prodigious mass of waters? Upon these unanswered questions depend others no less important. The aquatic animals of a former world undoubtedly lived in this sea; otherwise, we must admit of another sea free from heterogeneous materials. But did these animals continue to live in it during the whole process of precipitation; and did this process proceed so slowly and imperceptibly, that animal life was not interrupted by it, and that only remains of dead animals, such as the skeletons of fishes, and the covering of shell-fishes, were enveloped in the precipitates? Or, did animal life continue only during the state of solution; and were the myriads of aquatic animals found in beds of rocks buried in them alive? Many naturalists appear to entertain the latter opinion, from observing the agonies of death depicted in the distorted position of fishes in copper-slate, or from deriving the bituminous properties of stink-stone, as well as of marl, from the decomposition of animal bodies, of which such numerous vestiges are extant in these beds? In this way a plausible explanation is given of the phenomena of a former world that has perished. How, then, do they explain the constant appearance of so many species, which have continued without interruption for such an infinite length of time? Have these species been propagated by individuals who accidentally escaped destruction: or, Does a new race continually spring up again? But laying aside the difficulty of this explanation, the violent destruction of so many races of animals, is scarcely consistent with the general order of the universe, according to which, we behold every animal occupying its proper element, and fulfilling its particular destiny. We, therefore, involuntarily revert to the opinion, that those creatures, whose remains are preserved in beds of rocks, have lived continually in the sea, out of which the rocks were precipitated, in the same manner as the analogous species now living in the sea become enveloped in deposits still taking place, although on a comparatively small scale.

What has just been said does not entitle us to admit that the various parts of the earth have been, from time to time, overflowed with water. Yet are there other appearances which completely indicate such a change, namely, beds of coal, and the fossil remains of land animals. The carbonisation of roots of trees in clefts of rocks, and of marsh plants in peat-bogs, which takes place, as it were, under our own immediate observation; the transitions of bituminous wood into pitch-coal, the frequent presence of vegetables partly converted into coal, in the neighbourhood of beds of coal, and which are more abundant the nearer they are to these beds; and, finally, the chemical nature of coal, which is similar to that of vegetables, go to prove the vegetable origin of the older and independent coal formation.

Though some fossil vegetables might derive their origin, by being floated to quarters more or less remote from their native soil, as we find to be the case in many islands of the South Sea, and on other shores; on the other hand, neither the breadth and extent of beds of coal, nor the erect position in which fossil trees and reed plants are not unfrequently found in their neighbourhood, coincide with such an explanation. The plants, from which these beds were formed, once stood and grew in the place where they were buried; and, from these remains, we infer that they were entirely land plants, tree-ferns, Lycopodia, and other cryptogamia. It also appears undeniable, that the land, being once dry, was, during a longer or shorter time, covered with luxuriant vegetation; that it was afterwards overflowed with water, and then became dry land again. But, was this overflow of water produced by a sudden, violent, and universal catastrophe, such as we consider the deluge? Many circumstances leave room for opposite conjecture. If it is probable that the older or black coal is of vegetable origin, the plants from which it has originated, must have suffered an incomparably greater change than those of more recent coal formations. Their composition and their texture, afford evidence of a long operation of the fluid in which the changes were produced; and their situation, proves that the substance of the plants, though not entirely dissolved, was yet much comminuted, and was kept floating and swimming, and then precipitated. How can we, in any other way, account for the layers of sandstone and slate-clay, with which coal regularly alternates, so that from one to sixty alternate beds have been enumerated? How can we explain the combination of mineral coal with slate-clay, or account for the appearance of bituminous shale, flinty slate, of iron-pyrites and iron-ore, in the midst of mineral coal itself? We do not, however, admit of a repeated uncovering and covering of the land with water, and of a renewal of vegetation for every particular bed of coal; far from it, for violent inundations exhibit very different phenomena. These formations, like pure mineral formations, bear the evident impress of a lengthened operation, and of gentle precipitations; and whoever still entertains doubts regarding this, may have them completely removed by the condition in which vegetable remains are frequently found in the coal formations, by the perfect preservation of the most delicately shaped fern leaves, by the upright position of stems, and by other appearances of a similar character. It is also an important objection against the universality of the cover of water, notwithstanding the wide extent of beds of coal, that they are sometimes accompanied with fossil remains of fresh-water shells, from which we are entitled to draw the conclusion, that they must have been deposited in inclosed basins of inland waters.

From the beds of coal found in various situations among Alpine limestone, as well as in other secondary formations, under similar circumstances, we are at liberty to maintain that they are not indebted for their origin to any universal and sudden revolution.

When we proceed to the second division of coal formations, to brown coal, or to lignite, the principal difference we discover is, that the change which the vegetables have undergone, having taken place at a time when the chemical power had lost much of its energy, was incomplete; and besides, we observe in the different brown coal formations the same repetition of single beds alternating with other beds of rocks, the mixture of different minerals, and not unfrequently of upright stems. Some appear to be derived from sea plants, and others from fresh-water plants; but the greater proportion from land plants. They, equally with the beds of black coal, give evidence of a new overflow of water, and the water plants themselves, which never thrive at a great depth, and which frequently appear under prodigious beds of rocks, must have experienced such a change. But that change was scarcely of the kind which we understand by a deluge, and the frequent repetition of deluges indicated, according to some, by the repeated beds of coal from the transition to the newest tertiary periods, is hardly credible. It may be maintained, with more certainty, of brown coal than of black coal, that they have been formed in land water, and hence in limited and isolated basins of water, since fresh-water animals are their constant attendants.

Although the beds of coal of our secondary formations appear to have originated in a similar way with other mineral formations, and not by violent catastrophes, it is otherwise with a part of those vegetable remains which are met with in alluvial land. Subterranean forests, whose circumference, in some instances, extends about 70 square leagues, partly in a state of good preservation, and partly more or less decomposed, afford satisfactory proof of deluges, and have undoubtedly been covered up with earth by a violent eruption of standing or running water. But these are local effects, similar to what take place in our own day, but on a larger scale.

There are abundant fossil remains of land animals, resembling those of water animals, found in such a state of preservation, that we cannot suppose them to have been brought hither from distant places, and by means of currents. Their appearing in beds of rocks, or generally in aqueous precipitates, proves that the soil they first inhabited, must have been dry land, afterwards overflowed with water.

The appearance of what are called fresh water shells, in alternate beds with marine animals, being sometimes observed in newer flœtz rocks in great abundance, seems to indicate a reiterated retreat and return of the sea. But however meritorious the labours of naturalists, through whom attention has been directed to the subject, may be in other respects, we are nevertheless disposed to entertain doubts concerning their conclusions. In our own seas and ponds upon the coasts, we observe the same testaceous animals growing equally well in salt water, and in water nearly fresh; and, again, fresh water animals living in salt water[402]. By artificial means the inhabitants of the sea may be changed into inhabitants of fresh water; as fresh-water animals are, in their turn, converted into marine animals, so that, to decide concerning the proper element of each individual species is often matter of difficulty. Therefore, other circumstances besides that of containing salt must be taken into account. The occasional plenty, scarcity, or absolute want of food; the soil being sometimes sandy, slimy, or rocky; the depth, extent, agitation or tranquillity of the water; and, finally, the quality of the air contained in it, may be as instrumental in determining the habitation of these animals, as the materials which the water holds in solution. An excellent observer has indeed very lately shewn in a treatise, which supports the idea of fresh-water formations, that we possess no unerring character for distinguishing sea shell-fish from those of fresh water; but admitted, notwithstanding the transition above stated, we can draw a line of distinction between them, we must not forget that this investigation is neither regarding sea shell-fish now existing, nor of our present waters. We indeed draw our conclusion, and not without reason, from similar conformation, similar modes of existence. But one of two things must be; either that the shell-fish, whose remains are found in beds of rocks, lived in the water out of which these beds were precipitated, or the water in which they lived, was dislodged by other water containing the materials of the precipitations. In the first and more generally admitted case, the water was so different from the present water, whether salt or fresh, that we cannot infer from the inhabitants of the latter any thing concerning the inhabitants of the former; but we can confidently maintain, that a greater resemblance prevails between our sea and land water, than between either the one or the other, and that fluid which was inhabited by the shell-fish. In other respects, there remains no other difference between fresh and salt water formations, but that the bottom upon which the former is placed once contained land water; a fact worthy of observation: but the notion of enclosed basins, and of isolated formations originating in them, the way in which fresh water formations are supposed to have taken place, remained a long time unsatisfactory. Finally, we may be permitted to ask, upon what grounds they considered themselves entitled to ascribe to the former sea the continual possession of a portion of salt, while the salt precipitates appear only at particular intervals, and after long interruptions? If the sea occasionally contained a great, and sometimes a very small, quantity of salt, it might equally be at times altogether without it. And yet it deserves to be remembered, that the beds of rock, to which the salt formations are most nearly related, contain no petrifactions; that, therefore, the so-called marine animals are wanting in those periods during which we have any direct evidence of the presence of salt water.

There is, however, a geognostic fact, which, in preference to all others, has been cited in evidence of violent revolutions and deluges, that is, the appearance of conglomerates or of reproduced kinds of stone. Indeed, there might still be a wide field for investigation here, and more than one formation, which now passes for sandstone, might be acknowledged as an original and chemical production; without having occasion to go so far as Mr Gerhard does with greywacke,—that is, to consider them as immediate precipitates from the atmosphere. But still conglomerates sufficiently genuine, will remain from the transition period through all the subsequent formations, to serve as acknowledged monuments of destruction, as well as of the renovation of what was destroyed. These are the Codices rescripti, in the archives of the Earth, out of which, the antiquarian will one day decipher the almost obliterated traces of her former condition, as well as the history of her changes. Though these conglomerates deviate so much in their nature, and in the character of their origin, from chemical productions, they have yet among themselves this remarkable and common characteristic, that, with few exceptions, the older are much less varied in character, and more extensive in distribution, than the newer, and that, at length, the newest conglomerates become mere local appearances. But, in reference to the main question which engages our attention, we may conjecture that the beds of rocks from which the sea had never retreated, might be assailed by its floods and currents, and shattered to pieces, as happens even in our own time, and the fragments be again reunited into solid rocks, by means of the still remaining dissolved matter in the water. But of many conglomerates it is evident that they have been deposited on the dry land, in the same way as our gravels. Jupiter, who took counsel with himself, whether he would destroy the sinful world with fire or water, and at length decided for water[403], may not be so justly considered the author of these appearances, as Saturn, who devoured his children. Or, to be less metaphorical in our language, it may perhaps have been with the origin of conglomerates, as it is in our own day with the origin of fragments of rock and boulders, in which the rock being fractured in various places by the alternations of heat and cold, by the influence of air and atmospheric water, falls into pieces of greater or smaller magnitude, which are carried forward by the water, and gradually rounded in their progress, so that they assume a more perfectly globular shape the farther they are removed from their original situation. Therefore, as regards the foregoing enquiry, it is not an unimportant circumstance, that the long but continual rolling of the boulders during their rounding, appears to be much more efficacious than a rapid and violent impetus, and that, in this case, as in many other geognostic appearances, time rather than force is to be taken into account. Another circumstance, perhaps, corresponds with this, that the change produced by the weather, not only by the first disunion, but also by the progressive disintegration of the rocks, by the blunting of the edges and corners, by the diminution of the fragments, and generally in the origin of the boulders and fragments of rocks of every description, has just as much influence as the mechanical operation of the water; and that a great part of the land called Alluvial, generally owes its existence to this cause[404]. But if, upon farther consideration, the conglomerates appear to derive their origin in a similar way with rolled masses of gravel, they afford evidence, nevertheless, of the elevated station of the water in the neighbourhood, from which they had been before removed; for their conglomeration could take place only under water; and, with few exceptions, they occupy an incomparably greater elevation than any of the coal formations, or any of the beds of rocks which enclose the remains of land animals.

Geognosy certainly contains many facts, which cannot be explained, but by a change from dry land to the bottom of the sea, although our knowledge of them is still so imperfect, that we cannot hazard a probable conjecture respecting the numbers of these changes, whether they commence at the same or at different periods in the various quarters of the world, and whether they are local or universal. These changes appear neither sudden nor violent, such as we consider revolutions of the earth, but at all times proceed with silent and regular steps, and depend upon similar causes, concealed it is true from us, such as the universal retreat of the waters from their original height to the present bed of the ocean. We do not belong to those geologists who divert the world from its axis for the purpose of explaining the inequalities of its surface, at whose command the Earth sometimes opens her bosom to engulf the sea, and at other times the floodgates of Heaven are lifted up to pour down another ocean. He who reflects on the devastation caused by earthquakes, inundations and the fall of mountains, even though they are merely local appearances confined to particular quarters, cannot help putting the question to himself, how the order, regularity and connection exhibited by strata of rocks, could in any measure exist, if the same or similar accidents had happened throughout the whole world, and if mechanical power had operated with such energy, and to such an extent? All our knowledge of the structure of the earth, and of the existence of its inhabitants, declares rather a quiet uninterrupted and continually progressive advancement in its formation and development.

In the lapse of geological epochs, we observe a gradation of rock formations following one another, in which the latter, however remotely connected, still appear sufficiently similar to the earlier to indicate a common origin, till they at length terminate in simple formations, resembling those which are presently taking place. When the precipitates were exhausted, and the structure was completed, nay, even earlier, its destruction commenced; not that violent destruction by which lofty mountains are torn asunder and levelled, no uproar of nature, no gigantic struggle of the elements, such as we commonly conceive, but a decomposition of the strata of rocks to a greater or less depth, caused partly by chemical, partly by mechanical, but slow operating powers, what they wanted in intensity being compensated by the endurance of their operation. According to the common law of nature, deficiency of power is supplied by duration of time; for, of all the oracles which have been consulted concerning the formation of the earth, there is no one which can make such important revelations to us as the oracle of the age of mountains. These operations at the earth’s surface generally appear to have produced its present figure, and to have designed it for the habitation of numerous organic beings. This appears as early as a suitable element occurred; first, in water, then in land animals; and, like the formation of rocks, we observe a regular succession of organic formations, the later always descending from the earlier, down to the present inhabitants of the earth, and to the last created being who was to exercise dominion over them. But here occurs this important distinction: the organic world with youthful vigour renews itself daily, and decomposes its materials only to reunite them by fresh combinations in uninterrupted succession; while the powers of the inorganic world appear almost extinguished. Though this course of nature is manifest to our own observation, her resources and progress are, on the contrary, more concealed; and we can hardly lift the veil which conceals her, unless we follow Bacon’s advice, Turn back from rash theories, and follow observation and experience.

We have hitherto endeavoured to shew that incontrovertible geognostic facts indicate an alternate rising and falling of the water which covered the earth’s surface, but that they were not of a kind to justify the notion of violent revolutions, or of sudden and universal eruptions of the sea; and that, therefore, such deluges as the Mosaic deluge, recorded in the traditions of nations, were not revolutions of this description. If, according to the supposition of Cuvier, the earth’s surface inhabited at the commencement of the latter deluge has become the present bed of the sea, and the former bed of the sea has become the present dry land, then, according to the present state of geography, though only conjectural, we should be able to point out such portions of the earth as were overwhelmed by the catastrophe; and yet we have never heard that any one has hazarded such an experiment. In the constitution of the present habitable globe, we find no proofs remaining of such a revolution.

Among these revolutions of nature, we never reckon common inundations, such as take place at present from water overflowing its boundaries, though these also may produce devastation whose effects remain visible for an hundred years. But, in mountainous districts, another kind of aqueous eruption makes its appearance, and may be classed along with the traditions of a deluge. We very frequently, for instance, observe the valleys of high mountains forming a range of basins separated from one another by shorter or longer defiles, and opening through the last defile into a wider valley, or a marsh. The shape of these basins, or cauldrons, commonly lying above one another like so many stories, and the level surface of their water, leave no doubt of their being once enclosed lakes which were formerly blocked up by the barriers of the defiles, and which flowed towards the level country, as soon as the defiles were broken down by the waters. If no kind of historical monuments in the west of Europe bears evidence of those events, which, at least on a small scale, occur in our own times, this intimates that it was inhabited, not by an original population, but by a foreign or modern race of people; whereas those revolutions extended to remote antiquity. The numerous masses of rock found on both sides of the Alps to the height of 4000 feet, as well as in the plains of the north of Europe, at a great distance from their original position, and concerning whose coming hither so much light has lately been thrown by Messrs Buch and Escher, are a very probable proof of these debacles; while every circumstance renders it evident that these blocks were swept along by the currents thus created, to the place where they are now found. The Greek writers have also preserved accounts of such revolutions, which, although not unquestionably authenticated, are yet stamped with the impress of historical testimony. Herodotus has the following passages directly relative to the country where the Greeks place their second or Deucalionic deluge. “Thessaly must formerly have been an inland sea, surrounded by high mountains. On the east it was bounded by Pelios and Ossa, whose bases were united; on the north by Olympus; on the west by Pindus; and on the south by Othrys. Thessaly lay in the midst of these mountains in the form of a basin, into which, in conjunction with other copious streams, the five well-known rivers, the Peneus, the Apidanus, the Orochomenus, the Enipeus, and the Pamisos, emptied themselves. These rivers, which are collected in their basin from the mountains which encompass Thessaly, after their junction under the name of Peneus, in which they lose their former appellation, open towards the sea through a narrow valley. According to tradition, this valley and opening did not formerly exist; so that the rivers and the Lake Brebeis, which did not formerly bear these names, having their confluence in this place, rendered the whole of Thessaly an inland sea. The Thessalians affirm that Neptune opened the valley for the passage of the river Peneus, and they may perhaps be right. If we consider Neptune the author of earthquakes, and consider the violent concussion of the mountains caused by them as the work of this deity, we must, upon surveying these regions, confess that they owe their present shape to him; for the separation of every mountain appears to me to have been produced by some violent commotion of the earth.” Strabo makes mention of this tradition, which he thought worthy of belief, and accounts for the origin of the Vale of Tempe, which is the bed of the river Peneus, and likewise for the separation of Ossa from Olympus, by means of an earthquake[405]. In making this remark, we perceive that our theories which allow that earthquakes are to operate in forming the surface of the earth, have not even the merit of novelty. According to the last writer, similar eruptions of water must have originated in the lake Copais in Bœotia[406], in the lakes Bistonis and Aphnetis, in Thrace, and have been accompanied with huge devastation[407]. Diodorus Siculus[408] remembered a Samothracian tradition, according to which the Euxine Sea was once shut up on all sides. It afterwards burst through its mighty mound of kyanischen rocks to the Hellespont, and inundated a great part of the coast of Asia, as well as Samothracia itself. An objection started to the possibility of such an event is, that, from the observations of Olivier and General Andreossy, the shores of the Black Sea are, in most places, lower than those of the Bosphorus; and that its waters, therefore, even if they were considerably higher than they are at present, would more readily overflow the former than the latter. But since every rock exposed for such a length of time is daily crumbling down, it is a question, whether the shore of the Black Sea has undergone any alteration since that period; and we know that the eruptions took their direction, not so much from the low situation of the barrier, as from the nature of the rock of which it was constructed, being influenced by the weather, and from the rock itself being rent asunder. Be that as it may, the words with which Diodorus commences his narrative are remarkable, when he says, the Samothracian deluge happened earlier than those of other nations. It at least so far preceded others, that, in the estimation of the Greek historian, independent of the deluges of Ogyges and Deucalion, similar natural occurrences more or less authenticated were received as historical facts.

Finally, the effects produced by the bursting of lakes or debacles do not appear to be out of proportion to the devastation mentioned by the traditions of nations. To abide by our former example, floods which could carry along with them masses of rock of 50,000 cubic feet, were in a situation to bury a whole people; and the few individuals who might be preserved would undoubtedly have handed down the memory of such an event to remote posterity. Other deluges may have arisen from other causes, at a time when, as is shewn by numerous vestiges, lakes and rivers had a much greater elevation than at present; and, therefore, every overflowing of them must have produced greater and more extensive ravages.

From these last local eruptions of water, that is, from single limited districts, arose the mechanical precipitates known under the denomination of Alluvial Soil. Their situation, as the uppermost covering of the earth, as well as their origin, which takes place beneath our own observation, furnishes evidence of their being the most recent mineral formations; and it follows from their nature and connection that they were not produced by chemical means, but removed by the mechanical force of water. Since they, among other things, contain prostrate forests, and abundant remains of land animals, we conclude that they did not originate in the bed of the sea, but were floated and deposited upon the dry land by an overflow of land water. How is it conceivable that these precipitates have been covered by the ocean, since their deposition, and have, by means of an opposite change, become the dry land they are at present; and yet it must have been so, if they are to be considered as intimations of the Mosaic deluge.

The view now given, which is that of Henger in his Beiträge, is also advocated by other naturalists, and has lately been brought forward in an interesting manner in the Edinburgh Philosophical Journal[409]. We have been frequently requested to give the two views, in regard to the universal deluge, namely, that which maintains that it is proved by an appeal to the phenomena of the mineral kingdom; the other, which affirms that that great event has left no traces of its existence on the surface or in the interior of the earth. M. Cuvier’s Essay, and Professor Buckland’s Reliquiæ, are the best authorities for the first opinion; while numerous writers have advocated the second.

ON THE ACTION OF RUNNING WATERS.

A very great degree of power has been attributed to the waters which move at the surface of the earth, or in its interior. Many geologists have advanced the opinion, that they have scooped out the channels and even the valleys in which they flow, and formed the cliffs whose feet they wash; and many philosophers, naturalists and even geologists, still support this opinion, not only in some of its applications, but even in its whole extent.

In order to appreciate it, it is sufficient to observe with care the different modes of action of water set in motion by different causes, and the changes which it has operated upon the rocks and deposits upon which it has acted, from the most remote times to which history may reach.

We must, in the first place, successively examine the different sorts of action of the principal masses of water which are in motion at the surface of the earth, that is to say, the action of torrents, of rivers, of currents of the sea, or of great lakes, and that of waves.

We shall afterwards see what consequences are to be deduced from these observations.

1. Action of Torrents.

Torrents have a true degrading and scooping action upon the earth’s surface, but, by the necessary consequence of the sense which we attach to the word, this action cannot be exercised upon spaces of great extent, for a torrent is a water-course which has a great declivity. Now, on account of the little height which the most elevated summits of the globe have in comparison with the extent of its surface, this action cannot be very extensive; it can only, therefore, produce short and narrow ravines. This action, as all who have visited high mountain chains may have seen, is only often local and instantaneous; it presents no remarkable effect but upon the heaps of debris which cover the declivities of the mountains, and on broken rocks, partially disintegrated by other causes, and lastly on moveable deposits. The results of this action contribute to confine it within narrower limits still, by heaping up at the mouths of torrents in the valleys or plains, the debris carried down by these torrents. The elevation of the soil, which necessarily follows from the accumulation of these debris, diminishes with the declivity, the rapidity, and consequently the power of these water-courses.

Great masses of water moving rapidly, have a marked transporting power. Striking examples of this power have but too often been seen in Holland, by the breaking down of the dikes, and in Alpine mountains, in consequence of extraordinary rains during tempests, or from the rupture of some of the natural barriers of lakes. In these latter times (in 1818), the Vallée de Bagne experienced the terrible effects of this devastating power. Masses of ice having fallen towards the upper part of this valley, and accumulated there, raised a dike sufficiently compact and strong to block up the course of the Dranse. The waters of this river, rapid and pent up in certain parts of its course, as are all those of the high Alps, accumulated above this barrier of ice, and formed a lake which attained, at its maximum, 130 metres of mean breadth, from 3000 to 4000 metres of length, and 36 of mean depth, and consequently a volume of water estimated at about 29,000,000 cubic metres. Although, by means of operations conducted with equal skill and courage, about the third part of this volume was let off without danger, the remaining part having suddenly broken through the barrier of ice, was precipitated with an almost unexampled impetuosity of 11 metres in the second, into the Vallée de Bagne. In the first part of its course, and in the space of half an hour which the mass of water took in traversing a league, it carried away trees, dwellings, enormous masses of debris, and rocks already separated from their mass, as M. Escher, expressly says; it covered all the broad parts of the valley with rubbish, pebbles and sand, and carried the remainder of the substances which it had swept away, as well to the extremity of the valley, towards Martigny, as into the bed of the Rhone. The mass of water took an hour and a half in rushing from the glacier to Martigny. The same event took place from the same cause, and with nearly similar results, in 1595.

Torrents may therefore scoop out ravines in certain formations, and produce effects which appear considerable, because we judge of them by comparison with our own feeble means. But how diminutive and circumscribed are these changes produced in the configuration of the globe, compared with the long and broad valleys which furrow in vast numbers the immense surface of the earth, and to the formation of which neither the torrents nor great rivers which exist at the present day have in any way contributed, as we shall presently demonstrate.

2. Action of Rivers.

The action of rivers must be examined under two very different circumstances, or at two different parts of their course.

First, When they are compressed between mountains, whether at no great distance from their source, or even at the middle of their course.

Secondly, When they have reached broad valleys, whose declivity is slight, or plains which commonly surround their mouth.

In the first case, these rivers partake of the impetuosity and power of torrents. They often run with rapidity, and in great quantity, at the bottom of narrow and deep valleys: they are as it were inclosed in channels, whose vertical walls appear as if cut by art. The first idea which presents itself to all who have seen these appearances for the first time, and who are satisfied with first impressions, is, that these streams, which are pretty powerful and always very impetuous, have dug these deep grooves; and if sometimes the hardness of the rocks and the height of the precipices which form their sides, appear too great for those small streams that meander at their feet, what cannot be attributed to their immediate power is attributed to the continued action of time.

Without examining how long a series of ages it would be necessary to admit, before the rivers which we have mentioned above, and the water-courses encased in the deep valleys of the Alps, Pyrenees, Jura, Grampians, &c. could have scooped their valleys, on which their present action is so slow that no one has yet been able to estimate it; without examining if this long series of ages agrees with the phenomena, which preclude our attributing so remote an antiquity to the actual state of the earth’s surface, a question of too much importance to be treated indirectly; it will be sufficient to mention here four sorts of observations, in order to be persuaded, or at least to suspect, that the present rivers, even supposing them ten times the size that they are, could not have scooped out the deep channels at the bottom of which they run.

1. We must recur to the period when the ranges of hills which border the present valleys were not as yet scooped out, but were united in such a manner as not to leave any hollow between them, or merely a slight original depression.

This shallowness of the valley would be accompanied with an inconsiderable slope of its bottom. If, then, we suppose the same mass of water, it must run with less quickness, and consequently with much less power; and yet a very great force must be attributed to it, before it could have had the power of removing a portion of rock nearly represented by a recumbent triangular prism, having often 500 metres of breadth by a sometimes equal and often much greater vertical thickness. If, in order to get rid of this difficulty, we admit a volume of water incomparably larger than the present volume of the rivers to which so great effects are attributed, we must admit much more elevated and more extended mountains, to give rise to so great a volume of water.

Were we only detained by this hypothesis, and did not direct observation oppose itself to the admission of this disaggregating power and its effect, we might pass it over; but two other observations render the hypothesis inadmissible.

2. Historical records equally concur to prove that the rivers possessed of the greatest power which can be attributed to them, have no appreciable corroding action upon the rocks on which they move.

No one has maintained that the greater number of the cascades, cataracts, or rapids, long known and mentioned on account of their celebrity, have disappeared or have even sensibly diminished, nor consequently that the natural dike which the water had encountered in its course, has been worn or even completely disrupted. We do not find that cascades have changed into cataracts, and these again into rapids. The cataracts of the Nile have been spoken of from time immemorial, as always opposing an obstacle to the navigation of that river; the same is the case with those of the Danube, of the fall of the Rhine at Schaffhausen, &c. The famous cascades of the Alps and Pyrenees have been cited ever since writing was in use; and among all these examples we can scarcely find two or three cascades that have been lowered, or cataracts reduced in their level.

The only cascade which we can point out as having really diminished in height, is that of Tungasca in Siberia. We do not, however, assert but that there may be others. So many causes different from those of erosion may concur to lower a cascade, or even make it disappear almost entirely, that we are rather astonished at the small number of examples mentioned, than embarrassed by the objections which these examples might present to the opinion which we are defending: for the fall of a part of the rock which forms the cliff from which the cascade is precipitated; an abundant accumulation of debris at the foot of the cliff; a real destruction of the softer deposits, forming part of the strata of the mountain from which they fall, are sufficient causes for changing the height of waterfalls. These causes must present themselves pretty frequently; but how different is their action from that of erosion? This, if it existed, would extend from the source of the river to its mouth, and would have a considerable influence upon the configuration of the earth’s surface. Those which we have mentioned have, on the contrary, an action so limited and so local, as to be scarcely appreciable.

3. Allowing, for the moment, that a river, possessed of a vast erosive or disaggregating power, may have scooped out the valley in the bottom of which it at present flows, in a state of feebleness very different from its original state, we must account for the disposal of a vast mass of earth and rock, which filled up the valley before the river had removed it. It is not possible to suppose that it has been transported into the sea, which is often more than a hundred leagues from the valley; for we know that when rivers, on reaching the plains, lose their rapidity, they allow the matters to be precipitated which they held in suspension. Besides, we have shown that many rivers, on leaving the mountains, traverse lakes, in which they deposit all the earthy matters suspended in their waters. This deposition is particularly striking in all the considerable rivers, which descend from the ridge of the Alps toward the north-west and south-east of that chain of mountains. These rivers meet, at the opening of the valleys they flow through, lakes, which they traverse, and which seem intended for their purification. Thus, on the northern side, we see the Rhone traversing the lake of Geneva; the Aar, the Lakes of Brientz and Thun; the Reuss, the Lake of the Four Cantons; the Linth, the Lake of Zurich; the Rhine, the Lake of Constance. On the south side, the Lac Majeur is traversed by the Tessin, the Lake of Como by the Adda, the Lake Disco by the Oglio; the Lake of Guarda by the Mincio, &c. Now, these lakes, which are only themselves deeper parts of the valley, would have been filled up by the debris conveyed to the valley, if this valley had the origin attributed to it. Proceeding from one hypothesis to another, it might perhaps be supposed that these lakes may have been sufficiently deep to swallow up all the debris of the valley, without being chocked up. But, rather than admit such suppositions, why not grant that the same unknown cause which has scooped out the lake, has also scooped out the valley which is only a continuation of it?

4. But if facts had proved that the waters degrade the rocks, scoop them out, and perpetually remove their debris, we might perhaps be induced to admit that unknown causes, of which we are absolutely ignorant, and of which we can form no idea, have given to the original rivers the means of surmounting all these obstacles. Now, observation would seem absolutely to prove the contrary.

We have remarked, that rapid rivers which, in the bottom of valleys, fall in cascades, from rock to rock, which beat with violence against the walls which contain them, do not in any degree alter these rocks, and that, far from corroding their surface, they allow it to be covered with a rich coating of mosses, confervæ, &c. which could neither maintain itself, nor be formed at all, were the least portion of the surface of these rocks continually or even only frequently removed.

A much more striking fact is that which some of the great rivers present, such as the Nile, the Orinoco, &c. which flow in the equatorial regions.

These powerful rivers, when they have arrived at places where they are contracted, and, as it were, jammed in between two rocky walls, form impetuous cataracts. Their waters, endowed by the celerity of this fall with the greatest erosive power that can be attributed to this fluid, must necessarily have corroded, or at least worn, the rocks which they have thus beat against since the creation of our present Continent. Now, so far from removing the surface, they cover it with a brownish varnish of a peculiar nature.

It appears, therefore, well established, that water alone does not scoop those rocks, whose aggregation is complete, or which are solid; and that it does not wear them in any way, whatever be its quantity of motion.

We say water alone; and we must insist on this distinction, in order to make the preceding facts agree with other facts, which might seem contradictory.

We often see furrows scooped out on the walls that bound the narrows of rivers; we also see rocks rounded, and entirely destitute of moss. But let the facts be examined with attention, and we shall find that this erosion always takes place in the parts of their course, where, on account of the nature of the neighbouring soil, the torrents carry with them, in their risings (or floods), debris and detached stones from their banks; and it is by means of these stones that they wear the rocks which are in their bed.

It is very easy to appreciate these circumstances. It is remarked, that this erosion has never taken place at the sources of powerful springs. All the pebbles which had to be carried off have been so long ago, and the mosses which grow abundantly on the rocks at the level of the water, and in the bed of these torrents, have nothing more to fear from the destructive action of these solid bodies. The case is the same with the parts which immediately succeed a lake, or a great excavation, capable of arresting all the hard bodies carried off by the river. There the mosses appear in abundance; because they are not subjected to the action of any other substance than of the water alone.

The present rivers do not therefore appear to have any erosive power upon the rocks which are completely aggregated, when they act by themselves, and when no other cause, such as frost, decomposition, &c. has disintegrated the rock. The absence of these foreign circumstances is proved by the vegetation or the enamel which then cover the rocks exposed to the action of the water.

These rivers, in proportion as they remove from the rocks in the neighbourhood of the lofty mountains in which they took their rise, often gain in volume what they have lost in velocity; but the power dependent upon size rarely compensates that which they owed to rapidity; and although these large rivers still retain a transporting power, sufficient to carry along with them the obstacles which oppose themselves to their progress, they are far from presenting results of action so striking as those of torrents. They stir up, when flooded, or when they change place, the earth and mobile sand which cover their bottom, especially towards their edges, and transport them to some distance; but they scarcely move pebbles larger than an egg, which occur in their bed, and which have been brought there in other times, and under other circumstances. On thus transporting the comminuted and mobile mineral matters, they deposite them again in places where their current is relaxed by some cause, and thus raise the bottom of their bed in these places; they seek a new passage in the midst of the barriers which they have themselves constructed. The principal current is then borne, sometimes against one bank, and sometimes against the other; and when it comes to beat upon the foot of a steep part, composed of moveable soil, as the banks commonly are, in such cases, they really erode it, and make it fall into the river; and transport to another part of its course, the earth resulting from the destruction of the bank, and give rise to new obstacles. Hence the new deposites, which border rivers in all points where their current is slackened, and principally toward their mouth. It is sufficient for our present purpose to have referred to facts remarkable for their number, for the importance which they have had in regard to the modern changes of the configuration of the globe; and, lastly, in regard to agriculture and civilisation;—facts of easy observation, and which tend to prove, that the action of rivers, whose fall is not sufficiently rapid to entitle them to be considered as torrents, is not to scoop out their bed, either in the valleys or in the plains through which they flow, but rather to raise them, and to tend, consequently, rather to level and flatten the earth than to furrow it, more than it has been since the Continents have assumed the configuration which they now possess.