Part 17

Let us suppose, for instance, that a great irruption of the sea were now to cover the continent of New Holland with a coat of sand or other debris; it would bury the carcases of animals belonging to the genera Kangurus, Phascolomys, Dasyurus, Perameles, flying phalanger, echidna, and ornithorynchus, and it would entirely destroy the species of all these genera, since none of them exist now in any other country.

Were the same revolution to lay dry the numerous narrow straits which separate New Holland from the continent of Asia, it would open a road to the elephants, rhinoceroses, buffaloes, horses, camels, and tigers, and to all the other Asiatic quadrupeds, which would come to people a land where they had been previously unknown.

Were some future naturalist, after having made himself well acquainted with this new race of animals, to search below the surface on which they live, he would find remains of quite a different nature.

What New Holland would be, under the circumstances which we have supposed, Europe, Siberia, and a large portion of America, now actually are. And, perhaps, when other countries shall have been examined, and New Holland among the rest, it will one day be found that they have experienced similar revolutions, I might almost say, mutual changes, of productions. For, if we push the supposition farther, and, after the supply of Asiatic animals to New Holland, admit a second revolution, which destroyed Asia, their original country, those naturalists who might observe them in New Holland, their second country, would be equally at a loss to know whence they had come, as we now are to find out the origin of the races of animals that inhabit our own countries.

I now proceed to apply this manner of reasoning to the human species.

Proofs that there are no Fossil Human Bones.

It is certain that no human bones have yet been found among fossil remains; and this furnishes an additional proof that the fossil races were not mere varieties of known species, since they could not have been subjected to human influence.

When I assert that human bones have never been found among fossil organic remains, (I must be understood to speak of fossils or petrifactions, properly so called), or, in other words, in the regular strata of the surface of the globe; for in peat-bogs (tourbières), and alluvial deposits, as in burying-grounds, human bones might as well be found as bones of horses, or other common species. They might equally be found in fissures of rocks, and in caverns, where they may have been covered over by stalactite; but in the beds which contain the ancient races, among the palæotheria, and even among the elephants and rhinoceroses, the smallest portion of a human bone has never been discovered. Many of the labourers in the gypsum quarries about Paris, believe that the bones which occur so abundantly in them, are in a great part human; but I have seen several thousands of these bones, and I may safely affirm that not one of them has ever belonged to our species. I have examined at Pavia the groups of bones brought by Spallanzani from the Island of Cerigo; and, notwithstanding the assertion of that celebrated observer, I equally affirm, that there is not one among them that could be shewn to be human. The homo diluvii testis of Scheuchzer has been restored, in my first edition, to its true genus, which is that of the salamanders; and, in a more recent examination of it at Haarlem, allowed me by the politeness of Mr Van Marum, who permitted me to uncover the parts enveloped in the stone, I obtained complete proof of what I had before announced. Among the bones found at Canstadt, the fragment of a jaw, and some articles of human manufacture, were found; but it is known that the ground was dug up without any precaution, and that no notes were taken of the different depths at which each article was discovered. Every where else, the fragments of bone alleged to be human, are found, on examination, to belong to some animal, whether these fragments have been examined themselves, or merely through the medium of figures. Very recently, some were pretended to have been discovered at Marseilles, in a quarry that had been long neglected; but they have turned out to be impressions of tuyaux marines. Such real human bones as have been exhibited as fossil, belonged to bodies that had fallen into fissures, or had been left in the old galleries of mines, or that had been incrusted; and I extend this assertion even to the human skeletons discovered at Guadaloupe, in a rock formed of fragments of madrepore, thrown up by the sea, and united by water impregnated with calcareous matter. The human bones found near Kœstriz, and pointed out by M. de Schlotheim, had been announced as taken out of very old beds; but this estimable naturalist is anxious to make known how much this assertion is still subject to doubt. The same has been the case with the articles of human fabrication. The pieces of iron found at Montmartre are fragments of the tools which the workmen use for putting in blasts of gunpowder, and which sometimes break in the stone.

Yet human bones preserve equally well with those of animals, when placed in the same circumstances. In Egypt, no difference is remarked between the mummies of men and those of quadrupeds. I picked up, from the excavations made some years ago in the ancient church of St Genevieve, human bones that had been interred below the first race, which may even have belonged to some princes of the family of Clovis, and which still retained their forms very perfectly. We do not find in ancient fields of battle that the skeletons of men are more wasted than those of horses, except in so far as they may have been influenced by size; and we find among fossil remains the bones of animals as small as rats, still perfectly preserved.

Every circumstance, therefore, leads to the conclusion, that the human species did not exist in the countries in which the fossil bones have been discovered, at the epoch of the revolutions by which these bones were covered up; for there cannot be a single reason assigned, why men should have entirely escaped from such general catastrophes, or why their remains should not be now found like those of other animals. I do not presume, however, to conclude that man did not exist at all before this epoch. He might then have inhabited some narrow regions, whence he might have repeopled the earth after those terrible events. Perhaps also, the places which he inhabited may have been entirely swallowed up in the abyss, and his bones buried at the bottom of the present seas, with the exception of a small number of individuals, which have continued the species.

However this may be, the establishment of man in those countries in which we have said that the fossil remains of land animals are found, that is to say, in the greatest part of Europe, Asia, and America, has necessarily been posterior, not only to the revolutions which have covered up these bones, but also to those which have laid bare the strata containing them, and which are the last that the globe has undergone. Hence it clearly appears, that no argument in favour of the antiquity of the human species in these different countries can be derived either from those bones themselves, or from the more or less considerable masses of rocks or of earthy materials by which they are covered.

Physical Proofs of the Newness of the Present Continents.

On the contrary, by a careful examination of what has taken place on the surface of the globe, since it has been laid dry for the last time, and its continents have assumed their present form, at least in the parts that are somewhat elevated, it may be clearly seen that this last revolution, and consequently the establishment of our existing societies, could not have been very ancient. This result is one of the best established, and, at the same time, one of the least attended to in rational geology; and it is so much the more valuable, that it connects natural and civil history in one uninterrupted series.

When we measure the effects produced in a given time by causes still acting, and compare them with those which the same causes have produced since they have begun to act, we are enabled to determine nearly the instant at which their action commenced; which is necessarily the same as that in which our continents assumed their present form, or that of the last sudden retreat of the waters.

It must, in fact, have been since this last retreat of the waters, that our present steep declivities have begun to disintegrate, and to form heaps of debris at their bases; that our present rivers have begun to flow, and to deposit their alluvial matters; that our present vegetation has begun to extend itself, and to produce soil; that our present cliffs have begun to be corroded by the sea; that our present downs have begun to be thrown up by the wind: just as it must have been since this same epoch, that colonies of men have begun, for the first or second time, to spread themselves, and to form establishments in places fitted by nature for their reception. I do not here take the action of volcanoes into account, not only because of the irregularity of their eruptions, but because we have no proofs of their not having been able to exist under the sea; and because, on that account, they cannot serve us as a measure of the time which has elapsed since its last retreat.

Additions of Land by the Action of Rivers.

MM. Deluc and Dolomieu have most carefully examined the progress of the formation of new ground by means of matters washed down by rivers; and although exceedingly opposed to each other on many points of the Theory of the Earth, they agree in this. These formations augment very rapidly; they must have increased still more rapidly at first, when the mountains furnished more materials to the rivers, and yet their extent is still inconsiderable.

Dolomieu’s Memoir respecting Egypt tends to prove, that the tongue of land on which Alexander caused his city to be built, did not exist in the days of Homer; that they were then able to navigate directly from the island of Pharos into the gulf afterwards called Lake Mareotis; and that this gulf was then, as indicated by Menelaus, from fifteen to twenty leagues in length. It had, therefore, only required the nine hundred years that elapsed between the time of Homer and that of Strabo, to bring things to the state in which this latter author describes them, and to reduce the gulf in question to the form of a lake, of six leagues in length. It is more certain, that, since that time, things have changed still more. The sand thrown up by the sea and winds have formed, between the island of Pharos and the site of ancient Alexandria, a tongue of land two hundred fathoms in breadth, upon which the modern city has been built. It has blocked up the nearest mouth of the Nile, and reduced the lake Mareotis to almost nothing; while, during the same period, the alluvial matter carried down by the Nile, has been deposited along the rest of the shore, and has greatly increased its extent.

The ancients were not ignorant of these changes. Herodotus says, that the Egyptian priests regarded their country as a gift of the Nile. It is only in a manner, he adds, within a short period, that the Delta has appeared. Aristotle observes, that Homer speaks of Thebes as if it had been the only great city in Egypt; and nowhere makes mention of Memphis. The Canopian and Pelusian mouths of the Nile were formerly the principal ones; and the coast extended in a straight line from the one to the other; and in this manner it still appears in the charts of Ptolemy. Since then, the water has been directed into the Bolbitian and Phatnitic mouths; and it is at these entrances into the sea that the greatest depositions have been formed, which have given the coast a semicircular outline. The cities of Rosetta and Damieta, which were built upon these mouths, close to the edge of the sea, less than a thousand years ago, are now two leagues distant from it. According to Demaillet, it would only have required twenty-six years to form a promontory of half a league in extent before Rosetta.

An elevation is produced in the soil of Egypt, at the same time that this extension of its surface takes place, and the bed of the river rises in the same proportion as the adjacent plains, which makes the inundations of every succeeding century pass far beyond the marks which it had left during the preceding ones. According to Herodotus, a period of nine hundred years was sufficient to establish a difference of level amounting to ten or twelve feet. At Elephantia, the inundation at present exceeds by seven feet the greatest heights which it attained under Septimus Severus, at the commencement of the third century. At Cairo, before it is judged sufficient for the purpose of irrigation, it must exceed, by three feet and a half, the height which was necessary in the ninth century. The ancient monuments of this celebrated land have all their bases more or less buried in the soil. The mud left by the river even covers, to a depth of several feet, the artificial mounds on which the ancient towns were built.

The delta of the Rhone is not less remarkable for its increase. Astruc gives a detailed account of it in his Natural History of Languedoc; and proves, by a careful comparison of the descriptions of Mela, Strabo and Pliny, with the state of the places as they existed at the commencement of the eighteenth century, taking into account the statements of several writers of the middle age, that the arms of the Rhone have increased three leagues in length in the course of eighteen hundred years; that similar additions of land are made to the west of the Rhone; and that a number of places, which were situated, six or eight hundred years ago, at the edge of the sea or of large pools, are now several miles distant from the water.

Any one may observe in Holland and Italy, with what rapidity the Rhine, the Po, and the Arno, since they have been confined within dikes, raise their beds, advance their mouths into the sea, forming long promontories at their sides; and judge, from these facts, how small a number of ages was required by these rivers to deposit the low plains which they now traverse.

Many cities, which were flourishing sea-ports at well known periods of history, are now some leagues inland; and several have even been ruined, in consequence of this change of position. The inhabitants of Venice find it exceedingly difficult to preserve the lagunes, by which that city is separated from the continent; and notwithstanding all their efforts, it will be inevitably joined to the mainland.

We know, from the testimony of Strabo, that Ravenna stood among lagunes in the time of Augustus, as Venice does now; but at present Ravenna is a league distant from the shore. Spina had been built by the Greeks at the edge of the sea; yet in Strabo’s time it was ninety stadia from it, and is now destroyed. Adria in Lombardy, which gave name to the Adriatic sea, and of which it was, somewhat more than twenty centuries ago, the principal port, is now six leagues distant from it. Fortis has even rendered it probable that, at a more remote period, the Euganian Mountains may have been islands.

M. de Prony, a learned member of the Institute, and inspector-general of bridges and roads, has communicated to me some observations which are of the greatest importance, as explaining those changes that have taken place along the shores of the Adriatic. Having been directed by government to investigate the remedies that might be applied to the devastations occasioned by the floods of the Po, he ascertained that this river, since the period when it was shut in by dikes, has so greatly raised the level of its bottom, that the surface of its waters is now higher than the roofs of the houses in Ferrara. At the same time, its alluvial depositions have advanced so rapidly into the sea, that, by comparing old charts with the present state, the shore is found to have gained more than six thousand fathoms since 1604, giving an average of a hundred and fifty or a hundred and eighty, and in some places two hundred feet yearly. The Adige and the Po, are at the present day higher than the whole tract of land that lies between them; and it is only by opening new channels for them in the low grounds, which they have formerly deposited, that the disasters which they now threaten may be averted.

The same causes have produced the same effects along the branches of the Rhine and the Meuse; and thus the richest districts of Holland have continually the frightful view of their rivers held up by embankments at a height of from twenty to thirty feet above the level of the land.

M. Wiebeking, director of bridges and highways in the kingdom of Bavaria, has written a memoir upon this subject, so important as to be worthy of being properly understood, both by the people and the government, in all countries where these changes take place. In this memoir, he shews that the property of raising the level of their beds is common in a greater or less degree to all rivers.

The additions of land that have been made along the shores of the North Sea, have not been less rapid in their progress than in Italy. They can be easily traced in Friesland and in the country of Groningen, where the epoch of the first dikes, constructed by the Spanish governor Gaspar Roblès, is well known to have been in 1570. An hundred years afterwards, land had already been gained, in some places, to the extent of three quarters of a league beyond these dikes; and even the city of Groningen, partly built upon the old land, on a limestone which does not belong to the present sea, and in which the same shells are found as in the coarse limestone of the neighbourhood of Paris, is only six leagues from the sea. Having been upon the spot, I am enabled to adduce my own testimony in confirmation of facts already well known, and which have been so well stated by M. Deluc. The same phenomenon may be as distinctly observed along the coasts of East Friesland, and the countries of Bremen and Holstein, as the period at which the new grounds were inclosed for the first time is known, and the extent that has been gained since can be measured. This new alluvial land, formed by the rivers and the sea, is of astonishing fertility, and is so much the more valuable, as the ancient soil of these countries, being covered with heaths and peat-mosses, is almost everywhere unfit for cultivation. The alluvial lands alone produce subsistence for the many populous cities that have been built along these coasts, since the middle age, and which perhaps would not have attained their present flourishing condition, without the aid of the rich deposits which the rivers had prepared for them, and which they are continually augmenting.