10. Thefe precipitations put an end to all the great chemical operations which had been fet in motion by the addition of light to the mafs of other fubftances of which the earth was compofed at the epocha from which I began to trace its hiftory; for fince that time, no precipitation whatever has taken place in the fea. This circumftance, which M. DE DOLOMIEU has alfo afcertained, added to the continuance of the level of the prefent fea, is very remarkable, as being intimately connected with the whole courfe of the preceding operations. The level of the sea not having changed fince its refidence in its new bed, it is a proof that there have been no cavities opened, as before, at its bottom: and as the elastic fluids, which rushed out of thofe cavities, were the causes of the former precipitations, was fee thus, that the permanence of the fea at a fixed level, and the ceffation of the precipitations, are connected by a common cause. Thus the water of the prefent fea, is the refiduum (to this time permanent) of the primordial liquid, which at one time covered all the globe, and from which were feparated all the fubftances that we at prefent observe on the earth: and by the fame caufe, of no new caverns having been opened at the bottom of the fea, our atmosphere, one of the products of these chemical operations, acquired at the fame time a ftate fenfibly fixed: fo that we no longer fee on our globe any other general effects than fuch as proceed from the viciffitudes of the seasons, and the reciprocal actions conftantly taking place between the atmosphere and the furface of different fails.

11. I have now, Sir, accomplished the task I fet myself in my first letter, that of explaining, by phyfical caufes, all the monuments of the great revolutions that we find on the furface of our globe. Genera, Phyfics, Chemistry, and Natural Hiftory, have ferved to conduct me through these monuments, from a very ftriking epocha, namely, that in which light was added to the other elements of the earth, to the birth of our prefent continents, the precife characters of which have ferved me as guides in this refearch. I have called that series of events the Ancient Hiftory of the Earth, which embraces that portion of geological phenomena, in which we diftinguish only a fucceffion of periods, without any determination of time: I fhall therefore call that the Modern Hiftory which I am now going to enter upon, in which we shall have a fixed chronology.

HISTORY of the EARTH fince the Birth of our CONTINENTS.

12. The two first objects we have to confider in this new PERIOD of our globe, are, the change that took place in its external tempera ture at the time of the revolution I have been defcribing, and the ari, gin of the population of the new continents. With respect to the firstwe have to recollect, that the rays of the fun are not of themfelves calorific; that they do not become fo with regard to the earth, but, by

paffing

paling through its atmosphere, and falling on different bodies; and that thus they become calorific, only by producing the immediate cause of heat, namely fire, of which light conftitutes a part. We also know, that the production of fire by the rays of the fun, is, all things elfe being equal, more or lefs abundant, according to the state of the atmosphere and of the feveral bodies; and that the permanency of the fire, thus produced at the furface of the earth, whether free or combined with other fubftances, and confequently the prefervation of the beat produced by the rays of the fun, depends on the nature of the operations that take place in the atmosphere, and at the furface of the earth. Now, our atmosphere was formed by degrees, in proportion as the fubftances of our ftrata were precipitated in the liquid that produced them; and we see that it underwent fucceffive changes, by what happened to the vegetables of the earth, at the fame time that the races of marine animals also fuffered changes by fimultaneous modifications of the liquid. Laftly, we have feen, that thefe claffes of correfponding changes had, for an immediate caufe, certain fucceffive revolutions of the bottom of the fea. Here, then, is the point I fhall fet out from, to determine the first object of enquiry in this new state of the earth; an object to which the phænomenon obferved in the ftrata of the Northern latitudes conducts us, namely, fkeletons of animals, which at prefent exift only between the Tropics.

our

13. Since the great revolution which gave birth to the first lands on our globe, there has been none equally confiderable, except that which deftroyed thofe lands, and gave birth to prefent continents. The atmosphere must have again undergone a great change in this latter revolution. There happened certainly at that time alfo a very great change in the dry furface of our globe; fince the lands that were fwallowed up confifted only of primordial Arata: whereas the new continents have at their surface, and to a great depth, all the pofterior frata; fo that the primordial strata appear only here and there, owing to convulfions undergone by the whole mafs of ftrata.

1

14. Here, then, are two very great changes which have taken place on our globe at the birth of our continents, and from thefe may have refulted very fenfible modifications of the influence of the folar rays, not only with regard to heat, but with refpect to all their operations. Without doubt we could not conclude from thefe, arguing a priori, that certain animals, which formerly lived without the Tropics could live there no longer in the new ftate of things; for we are still too ignorant of the compofition of the atmosphere, to trace its causes and effects to this depth: but finding in our fuperficial loofe ftrata carcafes of elephants and rhinoceroses, in fuch a ftate of prefervation as proves they cannot have been depofited there a great number of ages, without the leaft reafon to fuppofe there has been any fudden change in the pofition of the earth with refpect to the fun, or any lofs of internal beat, we must have recourse to fome change in the phyfical caufes operating at the furface of the globe. Thus, then, confiderable charges in the nature of the atmosphere, and of the lands, which we know in general fenfibly modify the action of the rays of the fun, prefent them

felves to our view as caufes adequate to the explanation of the change that has taken place in the dwellings of elephants and rhinoceroses: nor is this the only phænomenon depending on this caufe; for, we also find, for inftance, in our fuperficial loofe ftrata, certain shells, the fpecies of which became extinct at the fame revolution, and others that fince that time have been found to exift only between the Tropics. Thus thefe hænomena, inexplicable by means of every flow caufe, which announce fome grand revolution of our globe, fuch as can embrace at once fo many other phænomena, which have nothing common between them but that they are all marks of a great revolution, come, by means of known phyfical caufes, to range themthemselves under that which gave birth to our continents.

15. The other object we have to fettle, before we enter on the hiftory of thefe continents fince their birth, is, the commencement of their population. In treating of this fubject in this place, I do not mean to fpecify any thing either with refpect to men, domeftic animals, or even of the principal plants that men cultivate; I fhall come to this in time: here I have nothing in view but the general object.

16. We have seen already, that in the very bofom of the ancient fea, the ftrata fucceffively enveloped carcafes of terrestrial animals, and above all, a prodigious quantity of vegetable fubftances, which could not proceed but from a great number of islands, already peopled, whole origin I have alfo explained, and traced their hiftory. When the Jea abandoned its former bed, the ifles which ftill exifted in it became the fummits of our mountains; and thence it is that the population of the new continents proceeded. The winds and rains tranfported to great distances the feeds of plants, birds, and other animals affisting— and thefe propagated, at the fame time that their nourishment was increafing, on the hills and plains, where, in the new ftate of things, the climate fuited them. Such is the general idea of this great Geological phænomenon, which what follows will determine and afcertain more particularly.

17. I now come to the hiftory of the new continents, delivered over to the influence of those causes which are at present operating before our eyes; and, following the track I have chalked out above, this hiftory will be chronological. Not that I propofe here to show that the revolution, the characters of which will be more and more afcertained, is no other than the Deluge of our Sacred Hiftory, according to the circumstances tranfinitted to us by Moses; but this I will fay now, that the common refult of the feveral investigations I am going into, will be, in the very first place, a confirmation of the sacred chro nology fince this event.

18. As the firft object in this enquiry, I fhall take up again the hiftory of vegetation, which alone embraces a very grand and varied fcene. The feeds of mes, graffes, heath, and a thousand other plants which we find growing in uncultivated lands were tranfported from the higher places, and carried over all the hills and plains; and the vast extent of sandy grounds became thus almost every where what we now call heaths. It is of this kind of uncultivated land I shall first treat. The annual remains of plants accumulating on

the

the fand, began to cover it with that blackish earth in which we find the prefent plants rooted. There are immenfe tracks of thefe lands which have yet received no cultivation, and on which, therefore, the ftratum of blackish foil is the entire refidue of all the vege tables which have grown and perifhed there fince the birth of our continents. In places too far from every habitation, for even the fhepherds to lead their flocks there, and where, therefore, the heath itfelf forms thickets; at whatever elevation they are above the level of the Sea, this blackish ftratum is found (always mixed with a fine fand brought from other places by ftrong winds) about a foot and a half in thicknefs. Now the progrefs of this ftratum is accompanied in many places with chronological monuments, and I will relate one of those I have mentioned, in treating this fubject much at large, in my Letters on the Hiftory of the Earth and of Man.

19. The firft inhabitants of the north of Germany were shepherds, who, as yet, had no fixed habitations; fo that the only monuments remaining of them are their tombs: they depofited the afhes of their dead in urns, which they buried in open places, principally on the heights, and they covered them with earth. We find a number of these tombs on hills ftill uncultivated: they are well known under the name of tumuli, which I fuppofe they received from the Romans, as they are nothing more than heaps of earth. Here then the anterior product of vegetation was removed; what has formed there fince, is the product of the fubfequent vegetation; and this epoch is marked by the ancient Germans, who, fince the inv: fion of Germanicus, began to collect together and build. I have dug through the blackifbftratum on a number of these tumuli, to compare its thicknefs with that of the general ftratum of the rest of the ground, and confidering the fmall difference found between them, we could not find by any means a fufficient time to answer to the literal Hebrew Chronology from the Deluge, which befides is lengthened by fome commentators. But here we are to confider, that before a layer of blackish mould could be formed, it was neceffary that vegetation fhould be fully eftablished on those lands; and in this a portion of time was employed that should be added to the immediate refult of obfervation, which, however, we cannot well afcertain. The fame uncertainty prevails in the commencement of all the phænomena that ascertain the great truth which I have here begun to unfold; but from the nature of the fpecial caufes which produce it in each of them, it will be found, that though a certain latitude of time is produced by thofe uncertainties, it is confined within fuch limits as will effectually oppose, not only all the fables or fyftems of Chronology that are not founded on Genefis, but even the conjectures of fome chronologers who have arbitrarily lengthened the period between NOAH and ABRAHAM.

20. The cultivation of the earth comes next to the fpontaneous products of vegetation. Every where, as we afcend in the hiftory of any fettled nation, we find cultivators of the land, and we can follow uninterrupted traces of new tillage; nevertheless we may conclude from the relations of travellers, that one half of our continents is ftill uncultivated. Certain fpots of ground, which had fomething in them

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BRIT. CRIT. VOL. IV. OCT. 1794.

to

to attract people, either for the eafinefs of culture, or as ferving well for communication between other places already cultivated, became the cradles of great nations; within thofe anciently cultivated lands, the traces of the progress of cultivation are not very vifible: but from them have iffued warms, as it were, of men, wanderers at first, afterwards cultivators; whence have refulted a number of centres of cultivation fcattered here and there in the firft deferts, which have not ceased fince, both to increase themselves and to send out fresh colonies.Every where this procefs continues round places adjoining to lands ftill uncultivated, and it is at a great distance from its end. Here then is a new fucceffion of operations, to which the birth of our continents has given rife; and in comparing my own obfervations on this head with those of other travellers, I have had occafion to remark, that the progress of cultivation has every where left such evident marks in places fimilar to thofe I have defcribed, that when we attentively confider the fubject, the afpect of the country, the names of places, the progrefs of their aggrandizement, their relations to each other in langnage, opinions, cuftoms, the beginnings of public works by the increase of their means, the national progrefs of the arts, commerce and luxury-in a word, every thing, in a retrofpective research, leads us, from every diftant point, to fome chief places, the history or traditions relating to which carry us back to the firft æras of the cultivation of our lands. Here is a ftudy very interefting, as may be feen by following what I have related at large (from obfervation) in my Letters on the Hiftory of the Earth and of Man, where I have at the fame time pointed out both the moral and phyfical caufes, which accelerate or retard the progress of that general tendency of spontaneous caufes, together with the induftry of man, to augment the productions of the ground; and Meffrs. DE SAUSSURE, DE DOLOMIEU, and RAMOND DE CHARBONNIERE have made the fame remarks.

21. It should not have been then in capital cities, in the midst of countries covered with the marks of ancient cultivation, that the hiftory of the human race inhabiting our continents should have been inveftigated; fince the traces of fucceffion being there effaced, the imagination has a free field to expatiate in: it fhould have been in these places which are fo numerous, where human induftry is ftill at work, driven by the neceffities of an increafing population, to augment the means of fubfiftance by extending cultivation. Then the evident hiftory of the cultivators of our land, comes in as a fupport to those facts that relate to Spontaneous vegetation, to fet afide the fabulous pretenfions of fome people to antiquity; fince it follows equally from both, that our continents themselves, can have no higher date than the deluge defcribed by MOSES: of which truth I fhall, as I go on, bring many other proofs.

22. Without yet quitting the hiftory of vegetation, we find a new Chronometer in our peat-grounds, a phænomenon which I alfo have defcribed at large in my Letters on the Hiftory of the Earth and of Man. Peat, as well as the blackish earth I have fpoken of above, is a product of vegetation; but the fpoils of the vegetables that form it, lofe much lefs of their bulk, and they retain their combuftible faculty.Thefe vegetables, at firft fimply withered, form a spongy mafs, always

foaked