blish, by reference to facts and inductions connected with the physical history of the earth, that the Mosaical account of it was a correct one. Geology was not then sufficiently studied in England to enable many persons to take an interest in these disquisitions, which at present are calculated, for the opposite reason, to excite so much attention. In two or three years afterwards, a volume was published in Paris, by the same author, which was an enlargement, and a great improvement, of the former collection of letters. This volume forms the ground-work of the publication before us. has undergone, we are told by the learned editor, a complete revision. It is further enriched by various communications from M. De Luc junior, nephew of the original writer, and which consist of geological observations conducted by himself and other distinguished geologists. Some of these contributions serve the purpose of either illustrating the positions, or correcting the errors of the first De Luc. Such observations from a quarter where so much knowledge of the subject has been acquired, accompanied by quotations from numerous writers on geology, English and foreign, place the great arguments of De Luc, which were advanced more than thirty years ago, before the world at this moment, with all the sanction that they can derive from being conformable to the latest discoveries in geology. As we have already observed, it was the great object of De Luc, to show that revelation and nature were not inconsistent, but that they were in close connection with each other. He proposed, therefore, to show-not by an appeal to the imagination of man, nor yet to his inductive powers exclusively, but to facts which every one might estimate for himself-that the narrative of the deluge in the sacred writings, is completely borne out by the most irresistible geological evidence. De Luc has even gone farther, in demonstrating that the progress of the formation of the globe is recorded with a remarkable accuracy, as to the succession of the process, in the chronology of Moses. It would seem that De Luc was led to the investigation of this important question in geology, by finding that the authors of the early systems promulgated in that science, had always built them on anti-Christian principles. They held that natural history had nothing to do with religion; and that they who believed in Christianity, might do so consistently with rejecting the first chapters of Genesis. It was plain to any man of common sense, that this courteous profession on the part of the system-mongers, was only a delusion by which they entrapped, finally alienated from the Christian creed, many an unenquiring nind; and we grieve to think that there should be any truth in the following representation, which we are not allowed to question, since it comes from the pen of De Luc himself.

'The consequence has been, that men of letters, without being naturalists themselves, but putting implicit faith in what was so positively asserted to be the evidence of nature, have more openly and more successfully revived

some historical and moral arguments, to which both Jews and Christians have long ago replied, and which would never have had any influence on the bulk of mankind, if there had not been an appearance of an appeal to nature. Neither will I reject her evidence; I will only show it, such as it is, to those who have suffered themselves to be carried away by misrepresentations of it.-Letter ii. p. 47.

Such were the admirable motives which led the illustrious De Luc to devote a genius of no ordinary penetration, and a life of patient industry, to the investigation of the truth respecting this intricate question. The success which he merited was attained by him, and the achievement which crowned his labours was but the consummation of a series of discoveries in the natural world, which have chiefly contributed to render geology the noble and interesting science that we now find it.

The first obstacle which De Luc had to combat, was the apparently settled conviction of the scientific world, that our continents were of very great antiquity. We are now speaking, not of centuries, but of colossal periods of time, if we may be allowed to use the expression; and therefore antiquity, in the language of geology, refers to a period far behind six thousand years. He saw that this principle once admitted, there was an end of the authority of Genesis, and he accordingly imposed on himself the task of enquiring into the truth of a proposition that was, up to his day, so implicitly received, and its consequences left to make whatever impression they might on the public mind.

It was to overturn this position, and to prove that not many ages have passed since the continental parts of our globe were abandoned by the sea, that De Luc undertook a series of curious and difficult researches, and ultimately constructed a theory for ascertaining the age of those continents, which is at once ingenious and highly reasonable. De Luc commences by the general statement that the whole mass of our existing continents is composed of various strata, the order of the superposition of them being pretty much the same on all parts of the earth. The lowest of the strata are found to be free from every vestige of organized bodies, but when we examine the superior series of strata, we discover those bodies, or relics of them. Each stratum, however, has a peculiar species of organized bodies to itself. Again, in the upper strata, we likewise detect the remains of animals and vegetables, which bear the most undoubted marks of having subsisted on the earth. In the great majority of the strata, however, and even in the loose strata at the surface of our soil, the most considerable portion of these remains consists of sea bodies. These facts warrant, in De Luc's opinion, the inference, that the strata, as we now see them, horizontally imposed upon each other, assumed this relation when held in suspense, as it were, in the sea, and that this mutual position, which they still retain, resulted from the sudden retreat of the

waters. But the strata are found broken, overthrown, and sunk in great masses, so that the continents exhibit on their surfaces the most ruinous appearances. What can have produced this great disturbance but some mighty revolution, which forced back the sea, and exposed the continents to those influences which have ever since their denudation been operating upon them? We shall stop here in our analysis of the theory, to dwell for a few minutes on the probability of what De Luc asserts, viz. that the land which we are now inhabiting, was an ancient bed of the sea. This author thinks that after any scientific enquirer has studied the continents with attention in all their parts, 'from their centres to their borders, from their greatest elevations to their lowest depths; when they have seen the regularity of the strata composing the whole of their observable mass, and the quantity of the marine bodies contained in these strata, it is impossible not to acknowledge that we are inhabiting an ancient bed of the sea. With respect to that great revolution by which the strata were disturbed, as we have already seen, De Luc gives us the following account.

'We have seen that the entire mass of our continents is composed of strata, produced by the sea while it occupied this portion of the globe. These strata, which we may every where unequivocally trace, notwithstanding the various accidents they have undergone, extend every where down to the present sea, of which, after this revolution, they constituted the new boundaries. On this account I shall call them continental soil.

'As soon as the sea had changed its bed, the rivers were formed upon the new continents and, arriving at the sea, began to deposit at their mouths the mud they brought down with them: the sea also, agitating the sand in the more shallow parts, drove it back towards its shores by the action of the currents and tides. From these two causes, new lands began to be formed, which, contiguously to certain parts of the original coast, occupied successively the place of the water. These new lands are every where as distinct from the continental soil, as a layer of sand or gravel in front of a house, is from the house itself; their existence evidently proves that the level of the sea has had no tendency to rise since it has occupied its present bed; for, in this case, it would have successively overflowed either every where, or near certain coasts, the sediments that were deposited on its shores; whereas there are new lands upon every coast, or in its vicinity. If, on the contrary, the sea had had a tendency to sink, the new lands would necessarily have a regular slope towards it, by which we might be able to measure the quantity of its depression since it occupied its present bed but all the new lands, on every coast, of whatever extent they may be, are sensibly horizontal. This phenomenon, then, amounts to an absolute demonstration, that the sea has undergone no change in its level since it has occupied its present bed.

But before the sea occupied this bed, it covered our continents, and thus existed at a much higher level. What barriers could then retain it? It was impossible they could be other than lands more elevated than itself, which consequently occupied the place where the sea now is, and we know certainly, from the quantity of the remains of vegetables and terrestrial

that

animals, which have been buried in our strata while yet under the sea, there did at that time exist such lands. Thus, in order that the sea should have retired from the surface of our present continents, other continents, which before served it for a barrier, must necessarily have sunk so as to form the basin which it at present occupies.

This is a necessary consequence of the above facts, and its evidence does not depend on our determining how this revolution happened; but we shall soon discover it, by continuing to pursue the train of causes established in my former Letters, of which I shall, in a few words, recall to your recollection such parts as the subject requires.

The state of disorder in which we find all our strata, could have been produced only by considerable and repeated subsidences of the greater part of their mass, at eras marked by their monuments. These subsidences of

the bottom of the ancient sea could proceed only from the successive formation of caverns within, into which the increasing crust of strata, from time to time, fell down. By this is to be explained that great phenomenon which has given birth to geology, namely, the disappearance, at the exterior, of a great part of the liquid which formerly covered the whole globe, at a level exceeding our highest mountains. We have also found, in this disruption of the caverns, from whence issued, each time, new expansible fluids, the chymical cause of the successive changes in the precipitations that took place in the liquid, as well as of the simultaneous changes undergone by the atmosphere, so visible from the history of vegetables and animals. Lastly, when tracing the course of these operations, I pointed out an epoch at which, whilst the liquid covered the whole globe, a more rapid enlargement of the caverns under one portion of the crust of strata occasioned its sudden depression; by which, added to the infiltration that followed of a great part of the liquid in the interior of the globe, it ceased to cover more than the part which had subsided, which at once formed the first sea, and gave birth to the first continents.'-pp. 183-185.

De Luc, it will be seen, has observed that in the retirement of the sea, the continents which became naked and dry, were, from the moment of their exposure, acted on by various influences. Now not only can we observe and define the effects of those influences, but we can also determine the length of time which they took in every instance to work the changes observable in the exposed lands. Thus then we are furnished at once with a series of natural chronometers, whose evidence cannot be mistrusted. The ingenious theory of De Luc therefore comes to this; that all those parts of our continent which were capable of change, began to be changed on the retirement of the sea: from our own observations and experience, we can determine the time it has taken to effect the modifications which we observe in our continents; on these data we may properly proceed to ascertain the ancient or more recent origin of our globe.

Nothing can be more elaborate and ingenious than the manner in which De Luc has ascertained the effects of those operations to which we have alluded; and after conducting us through a series of most learned and beautiful illustrations, derived from natural

history, he concludes by almost demonstrating, that they all show the impossibility of carrying back the origin of our continents to a period more remote than that, which the Mosaic chronology has assigned to them. Amongst the phenonomena which De Luc enlists in his catalogue of natural chronometers, are to be found those of the collection of vegetable earth produced by the decomposition of plants on uncultivated soils; the natural history of peat mosses; the extension of snow and ice on high mountains; the accumulations of fallen materials; alluvial lands formed by rivers along their course; maritime new lands, &c. The descriptions of a few of these phenomena we shall transcribe from the author.

The seeds of mosses, grasses, heath, and a thousand other plants, which we find growing in uncultivated lands, were transported from the loftier spots, 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 sands, and other soils immediately favourable to vegetation, began to cover them with that blackish earth (humus), in which we find the present plants rooted. There are immense tracts of these lands which have yet received no cultivation, and on which, therefore, the stratum of blackish soil is the entire residue of all the vegetables which have grown and perished there since the birth of our continents. In places too far from every habitation, for even the shepherds to lead their flocks to, and where the heath alone vegetates, at whatever elevation such spots are above the level of the sea, this blackish stratum is found (always mixed with a fine sand brought from other places by strong winds) about a foot and a half in thickness. Now the progress of this stratum is accompanied in many places with chronological monuments, and I shall describe one of those I have mentioned, in treating this subject much at large, in my "Lettres sur l'Histoire de la Terre," &c.

The first inhabitants of the north of Germany were shepherds, who, as yet, had no fixed habitations; so that the only monuments remaining of them are their tombs: they deposited the ashes of their dead in urns, which they buried in open places, principally on the heights, and covered them with earth. We find a number of these tombs on hills still uncultivated they are well known under the name of tumuli, which, I suppose, 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 since, is the product of the subsequent vegetation; and this epoch is marked by the history of the ancient Germans, who, after the invasion of Germanicus, began to collect together, and build. I have dug through the blackish stratum on a number of these tumuli, for the purpose of comparing its thickness with that of the general stratum of the rest of the ground; and considering the small difference found between them, we could not find by any means a sufficient time to correspond with the literal Hebrew chronology from the deluge, which certain commentators have seen reason to lengthen. But here we are to consider, that before a layer of blackish mould could be formed, it was necessary that vegetation should be fully established on those lands; and the por