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In giving to the treatise here announced the name of an Essay on the Theory of the Earth, the Editor has taken a liberty that is certainly not warranted by the original. The title of the French work makes no mention whatever of the theory of the earth. The fact is, that M. CUVIER having published, in the Annales de Museum, a succession of memoirs on the fossil remains of animals found in the strata around Paris, (of which an account was given in the 20 th vol. of this Journal), was very naturally led to extend an inquiry, that became ever moment more interesting, to the fossil remains of land animals, wherever they had been found. His subject being thus enlarged, he has united the parts of a most ingenious and laborious investigation, in one work, comprehending four volumes in quarto, under the title of Recherches sur les Ossemens Fossils des Quadrupedes.
To this valuable and interesting book he has prefixed a Dissertation, (Discours Preliminary), the same that appears here as an Essay on the Theory of the Earth. We are not sure that the author himself will be very thankful for this change of appellation. The preliminary discourse is a general view of the conclusions derived from certain animal remains, compared with the mineral beds in which they are contained, and with the principles of comparative anatomy. This subject, though of great importance, and of no small extent, is yet of too limited a nature to be regarded as a theory of the earth. A name that would have more exactly described the work, without departing from the conciseness essential to a title-page, might easily have been devised. Considerations, for instance, on the Fossil Remains of Quadrupeds, would have been a title much more appropriate.
This translation has been made with singular expedition. The work was received about the middle of last summer; and the translation made its appearance in the beginning of winter. It seems, notwithstanding this haste, to be executed not only with fidelity, but with some degree of elegance; and the editor, Professor Jameson, has added notes, besides giving a very distinct and concise view of Cuvier's principal geological discoveries, which cannot fail to be very acceptable to those who have not an opportunity of perusing the large work and which will be found very useful by those who have. The Dissertation begins with a sketch of the present condition of the earth's surface.
It is known, that the lowest and most level parts of that surface, when pierced to a great depth, exhibit horizontal strata of rock, composed of different materials; and, in particular, abounding with marine productions. Similar strata compose the hills even to a great height. The shells are often so numerous, as nearly to constitute the main body of the strata; and sometimes in so perfect a state, that their most delicate parts are completely preserved, their sharpest ridges, and their finest processes. The levels on which they are now found, are far above that of the ocean, and at heights to which the sea could not reach by the action of any known cause. Every part of the earth, every continent, and every island, exhibits the same phenomenon. We are therefore unavoidably led to conclude, that the sea, at one period or another, has covered all our plains, and has remained there for a long time in a state of tranquility.
The latter circumstance was necessary for the formation of deposits so regular and extensive as those in which many of the marine exuviates are contained. The traces of revolution become still more apparent when we ascend a little higher, and approach nearer to the great chains of mountains. Beds of shells are still found in these situations, quite as numerous also, and as well preserved, but not of the same species with those in the less elevated regions. The beds which contain them, are not in general horizontal, but are often highly inclined, and sometimes even vertical.
In the plains and low hills it was necessary to dig deep, in order to discover the succession of the strata; but here we perceive it by means of the valleys which slow or violent action has produced, and which disclose the edges of the strata to the eye of the observer. These inclined or vertical strata, though on a higher level, do not rest on the horizontal strata of the plains, but, on the contrary, are situated under them. The level are in fact placed on the declivities of the inclined strata; and when we dig through the horizontal strata in the neighborhood of the inclined, these last are invariably found below the other. Sometimes, indeed, the summits of the inclined strata are surmounted by the horizontal, and the former are therefore of more ancient formation than the latter. Having, however, been formed, as they must necessarily have been, in a horizontal position, they have been subsequently shifted into their inclined or vertical situation, and that too before the horizontal strata were placed above them. The sea, therefore, previous to the formation of the horizontal strata, had formed others, which by some means had been broken, lifted up, and disturbed in a thousand ways.
This second result is not less obvious, nor less clearly demonstrated, than the first. Amid the changes which have thus happened, both to the sea and the strata it had deposited, it was hardly possible that the same species of animals should continue to live. Accordingly, not only the species, but even the genera, change with the strata. The shells in the more ancient formations have figures peculiar to themselves; and they gradually disappear, till they are not to be found at all in the more recent beds, and still less in the seas which now exist. On the contrary, the shells of the recent strata resemble those which still exist in the sea, and in such a degree as to appear of the same genera. Indeed, in the last formed of these strata, there are some species which the eye of the most exert naturalist cannot distinguish from some of those which at present inhabit the ocean.
Hence it is reasonable to conclude, that a succession of changes in animal natures has taken place, corresponding no doubt to that in the chemical properties of the fluid which they inhabited. When the sea last receded from our Continent, its inhabitants were not very different from those which it continues to support. When we ascend to point of still greater elevation, and advance towards the summits of the highest mountains, the remains of marine animals grow more rare, and at length disappear entirely. We arrive at strata of a different nature, which contain no vestiges at all of living creatures: Nevertheless the crystallization, and many other characters of these rocks, show that they have been formed in a fluid; their inclined position and their slopes, show that they have been moved and overturned; and the oblique manner in which they sink under the shelly strata, shows that they have been formed before them. We are thus brought to the primitive or primordial mountains, which traverse our continents in various directions, forming as it were the skeleton of frame work of the globe. In the disposition of these rocks, a certain degree of order and regularity is observed to prevail, insomuch that wherever the more recent strata have been dug through, and the external crust of the earth penetrated to a considerable depth, the same order of stratification is generally found.
The crystallized marbles never cover the shelly strata, and the granite mass never rests on the crystallized marble. This arrangement is never inverted, and, though some members of the series may be wanting, there is no instance in which, were they are present, they do not preserve nearly the same place relatively to one another. It is impossible, therefore, to deny that the waters of the sea have formerly, and for a long time, covered those masses of matter which now constitute our highest mountains; and farther, that these waters, for along time, did not support any living thing. After this sketch of the natural history of the globe for the ages that are past, CUVIER proceeds to examine the changes which are happening at present on the surface of the earth. There are, says he, four causes in full activity, which contribute to change the condition of the earth's surface. These are, the rains and thaws which wear down the steep mountains, and occasion their fragments to collect at their bottoms; -- the streams of water which sweep away these fragments, and deposit them when their current is abated; -- the sea, which undermines the foundations of the more elevated coasts, and throws up hillocks of sand where the shore is flat; -- and finally volcanoes, which pierce through the most solid strata, and either elevate or scatter abroad the vast quantity of matter which they force up from below.
These are the different causes of change, the effects of which our author endeavors briefly to trace and to estimate. He seems to consider them, on the whole, as but of small amount, and as inadequate to produce those changes which have undoubtedly taken place over the face of the earth. He next treats of the astronomical causes of revolution on the surface of the Earth; such as, the change in the position of the Earth's axis; in the obliquity of the Ecliptic; the rapidity of the Earth's rotation, & c. These he considers, and we believe justly, as unsupported by evidence from facts, or from the principles of physical astronomy.
To this general remark, we would only beg leave to offer one exception, derived from the spherical figure of the Earth. Many circumstances make it probable, that this figure, now so nearly adjusted to that which the centrifugal force, arising from rotation on its axis, would have given to a fluid mass of the magnitude and mean density of the earth, has been acquired by the slow progress and alternation of the waste, and renovation of the strata which compose the earth. If this be true, the original figure of the earth may have been extremely unlike the present; it may have been vastly irregular; and in the course of the changes which it has undergone, the axis of rotation may have changed its position, and have passed through a series of variations, that may have affected the distribution of the waters on the surface of the earth, the proportions of heat and cold, and the characters of the animals that inhabited the ocean. Such causes, however, are not considered by our author as sufficient to explain those changes in the animal kingdom which he has done so much to ascertain. "The irruptions, " says he, " of the sea, and its retreats, have neither been slow nor gradual; the catastrophes have been sudden: And this is easily proved, especially with regard to the last of them, the traces of which are most conspicuous. In the northern regions, it has left the carcases of some large quadruped which the ice had arrested, and which are preserved, even to the present day, with their skin, their hair, and their flesh.
If they had not been frozen as soon as killed, they must quickly have been decomposed by putrefaction; but this eternal frost could not have taken possession of the regions which these animals inhabited, except by the same cause which destroyed them. This cause must therefore have been as sudden as its effect. The breaking to pieces and over turnings of the strata which happened in former catastrophes, show, plainly enough, that they were sudden and violent like the last; and the heaps of debris and rounded pebbles which are found in various places among the solid strata, demonstrate the vast force of the motions excited in the mass of waters by these over turnings. " Nothing is more certain, than that all the changes which we discover on examining the interior of the earth, are not to be ascribed to such slow operating causes as are now at work on the surface. Of this truth we are fully convinced, though we are perhaps disposed to ascribe much more to those causes than the French naturalist is willing to allow. "The necessity, " he observes, "to which naturalists have been reduced, of seeking for causes different from those which we still observe in activity, is the very thing which has forced them to make so many extraordinary suppositions, and to lose themselves in so many erroneous and contradictory speculations, that the very name of their science, as I have elsewhere said, has become ridiculous in the opinion of prejudiced persons, who, only seeing the systems which it has exploded, forget the extensive and important series of facts which it has brought to light and established. " The author takes occasion, in a note, to explain the opinion to which he here alludes. "When I formerly mentioned, " says he, "the science of geology, I only expressed a well known truth, without presuming to give my own opinion, as some respectable geologists seem to have believed. If their mistake arose from my expressions having been rather equivocal, I take this opportunity of explaining my meaning. " We have great pleasure in meeting with this explanation; for we had indeed supposed that CUVIER, in the passage here referred to, was subscribing to the opinion which he expressed; and were sorry to think that a science, of which we thought favorably, notwithstanding the mistakes into which its followers had often fallen, should have come under the censure of a critic so judicious and well informed.
We are glad to find that in this respect we were mistaken. "Whence comes it, " (says he) "that there should be so much contrariety in the solutions of the same problem given by men who proceed on the same principles? This may have been occasioned by the conditions of the problem never having been all taken into consideration, by which it has remained hitherto undetermined, and susceptible of many solutions, all equally good, when such and such conditions are abstracted, and all equally gad, when a new condition comes to be known, or when the attention has been directed to some known condition which had been before neglected. " For our part, though we see in all geological systems great defects, and in some of them great absurdities, we cannot but think that they are steps by which men have approximated, and are gradually approximating to the truth. The discovery that a theory is erroneous, brings us nearer to that which is right; and by successive exclusions, we advance gradually to the truth. Philosophy affords but few instances where opinion has settled on what is right, before it had wandered through all the suppositions that are wrong. It has been already mentioned, as one of our author's general positions, that the cause of t...
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