teen fully equalled by the absurdity of their notions. The mad and childish reveries of Demailet, Lamanon, and Bertrand, would alone amply justify all the expressions of contempt and derision which have been directed against geology; and even the vigorous minds of Kepler Descartes, Burnet, and Buffon, were found to sacrifice to their respective hypotheses relative to our globe, not only all the rules of philosophy but also the plainest dictates of common sense. Nor can we take upon us to affirm that even Werner himself has not, on some occasions, generalized too hastily; and as to Hutton, his doctrines present themselves to our' eyes in no other light than that of a geological romance. These two names, however, divide at present the scientific world, as to the leading views which are entertained respecting the crust of the earth; and the authority of Hutton or of Werner has long superseded all reference to more ancient authors, on this amusing and interesting study. We shall therefore, before entering with Professor Kidd, upon the consideration of the limited and imperfect evidence which as yet has been produced in support of any geognostic theory, give a brief sketch of those which have been advanced by the German and the Scottish philosophers whom we have just mentioned.

The hypothesis which Dr. Hutton constructed to explain the origin of the earth's surface and the relations which subsist among its component parts, surpasses, in point of elegance and simplicity, every thing that has yet been engrafted upon the speculations of science. He perceived, in the present crust of our globe, the debris of former continents with all their hills and mountains together with the remains of a thousand generations of animals and vegetables, the monuments of art and the labours of countless ages; all which having undergone a process of renova tion in the depths of the ocean, was again exposed to the sun ashabitable land, fitted to support new races of animals, and to become the theatre of a new order of events. But the causes to which the renovated earth owes its existence are, according to the principles of this theory, already exerting their power to hasten its periodical catastrophie. The rains, the frost, and the very air of the atmosphere, are constantly wearing down the hardest rocks; and thus, those stupendous chains of mountains which stretch over all our continents, and constitute as it were the frame-work of this planet, are undergoing the operations of an incessant waste, and are already lowering their heads towards their parent ocean. All that is at present above the level of the waters will, says the Huttonian, sink in the course of ages to the bottom of the sea; where, by the operation of the central fires, the scattered materials will be again consolidated and reorganized into strata, and be once more elevated to the light of day. Thus,

1

is established a succession of grand phenomena, of which as the commencement cannot be traced, neither can the end be anticipated. Decay and renovation follow each other according to determinate principles, and the perpetuity of the system seems to be provided for in the very frailty and mutation of its parts.

Nothing can appear, in the shape of a philosophical hypothesis, more brilliant and captivating than this; but being founded on the most unwarrantable and gratuitous assumptions, the Huttonian theory is not in any respect entitled to our regard, as an interpretation of nature. There is not only no ground for believing that a mass of fire exists in the interior of the earth; but, on the contrary, the slightest inspection of the mineral kingdom renders it irresistibly convincing, that fire could not be the instrument employed in consolidating the parts, and determining the relations of fossil bodies. In all mountain rocks not strictly primitive, there are found organic remains, both animal and vegetable, of the most minute and delicate structure, exhibiting still uninjured fibres more slender than the human hair, and tubular vessels which only the microscope can detect. Is it possible to imagine that such a feeble organization could resist the operations of a fire, which must have fused immense rocks of quartz, and rendered liquid all the granite of the Alps and Andes! Would the leaf of a tree, a sprig of fern, or the shell of a fish, remain entire and impassive, while the most stubborn minerals were melted like water! With regard to the argument in favour of the Huttonian hypothesis, which has been drawn from the character of sandstone and conglomerate rocks, it has really no weight whatever, because the appearances in question are more easily explained on the principles of Werner; and the same observation is strictly applicable to the natural history of veins, which, in the greater number of instances, exhibit the most un-: equivocal proofs of a chrystalline origin. While, however, we thus express our opinion of Dr. Hutton's theory, and hesitate not to pronounce it totally irreconcilable both with the facts and principles of mineralogy, we take pleasure in declaring our complete concurrence with Professor Kidd in acquitting him of all intentions hostile to religion.

Of the Wernerian theory the leading doctrine seems to be, that all the materials of which the crust of the earth is composed were at one time held in a state of solution in the great chaotic water, and that they were consolidated in a certain order and succession, first by means of chystallization, and afterwards by mechanical deposition. From an attentive examination into the position and connections of the various strata, Werner was convinced both that they had been formed by means of water, and also that some of them had been formed at an earlier period

than others. The most ancient rocks bear a well marked cha racter derived from their chrystalline formation, and, as far as his observation extended, they were never found to contain either vegetable or animal remains; thus rendering it manifest, as Werner himself inferred, that they had been deposited from the chaotic fluid, prior to the creation of organized bodies. These rocks constitute the primitive formation of the Wernerian school, and consist chiefly of granite, or of its component parts felspar, quartz, and mica, together with clay-slate, porphyry, serpentine, and some others. From their position, which is generally much inclined and sometimes even vertical, the primitive rocks compose the principal elevations of our globe, while at the same time they descend under all the other strata, and form a bed or support for the newer precipitations and depositions. Next in order to the primitive come the transition rocks, which are supposed to have been formed after the waters of chaos had subsided so far as to expose the summits of the mountains; and the precipitations from the original solvent taking place at the same time with the deposition of the detritus which the action of the waters had already detached from the primitive rocks, give to this formation a mixed character; the rocks being partly chemical or chrystalline, and partly mechanical or composed of fragments. In these two, organic remains first begin to appear; and hence, as well as from the circumstances just mentioned, Werner conceived that this formation took place when the earth was passing from the chaotic to a habitable state. It is accordingly from this supposed epoch that they are denominated transition rocks. At this stage of the process, as might naturally be expected, the chemical pre cipitations become less frequent, and as the primordial waters still covered all but the elevated parts of the earth, their action on the newly-formed rocks would, it might be imagined, effect a considerable disintegration. This appears actually to have been the case; for the third or flat formation is composed principally of the sand and minute fragments which seem to have been washed from the two former; and the chrystallized rocks in this series bear a very small proportion to the mechanical, but a proportion however which corresponds exactly with the diminished quantity of matter which the waters are now supposed to have retained in solution. As a proof that the rocks of the third order have been deposited from a mechanical mixture, they are generally found arranged in horizontal beds of strata; and that their epoch is considerably posterior to the primitive, is reudered manifest by the abundance of organic remains which are every where scattered among them; and these, it has been observed, increase in variety and quantity as the formation on other accounts is reckoned more recent. The alluvial or fourth formation is obviously composed.

of

of the materials which have been worn down and washed away from the mountains and high land, and afterwards deposited either in vallies far above the level of the sea, or on the banks of rivers and along the coasts of estuaries. The stony masses which this formation contains exhibit the most satisfactory marks of having been rolled and agitated in water; and the rich mineral stones which usually characterize the alluvial depositions of mountainvallies bear testimony to the same origin. The fifth and last formation of Werner is the volcanic, including rocks both of true and pseudo-volcanic production, which, of course, are very local and partial in their occurrence and require no explanation.

The great merit of the Wernerian geognosy, as it strikes us, is that it hardly seems to involve an hypothesis, as far at least as regards its leading principles. It is obvious from the nature and constitution of the mineral substances which compose the crust of the earth, that they must have been formed in a fluid state; and as fluidity must proceed either from fusion or from solution, the enquiry is narrowed to the consideration of these two causes. Now, passing over every other objection, it may be asserted in the most positive manner that it is impossible the stratified rocks could have been consolidated by fire, because they contain, as we have already mentioned, organized bodies in an entire and perfect state; which must have been completely destroyed by such a degree of heat as would be necessary to fuse basalt. Besides, in the series of strata which make up the floetz, formation, we have coal and clay under the most stubborn and refractory rocks, so, according to the Huttonian hypothesis, we have to encounter the monstrous imagination, that the central fire melted hornblende, felspar, and agate, through a stratum of coal which it did not char, and through a bed of clay which it failed to indurate. Water therefore must be regarded as the sole cause of fluidity, and the chrystallized form of the primitive or oldest rocks lends the strongest confirmation to this opinion. It is an opinion, too, which corresponds with our earliest notions on this subject, and with the highest authority which can be referred to on matters of science. The only conception we can form of chaos is that of a mass of dark and troubled water, in which were contained, in a state of solution, the materials of which the outer coat of the earth is formed, and from which they were successively precipi tated according to laws impressed upon them by the Almighty Creator. Nor let it be imagined that the period of time which must have elapsed before the third formation, being chiefly mechanical, could be deposited, conveys any thing incompatible with the Mosaical history of the creation. It is only necessary to call to mind that Moses does not profess to give any account of chaos, and that it is not until the earth is nearly fitted to become

the

the habitation of men that the sacred historian enters into particulars. Besides, the object of the brief statement with which the book of Genesis commences, was evidently not to teach a system of astronomy or any other branch of natural science, but to impress upon the minds of the Israelites that God is the Creator of the world and of every thing contained in it; and we perfectly agree with Professor Kidd in thinking, that from such slight materials to attempt to explain the details of geological phenomena, or to limit the progress of knowledge by the literal interpretation of so brief and mysterious a history, are equally unreasonable. Were it necessary, however, to point out how scriptural truth is confirmed by the deductions of science, and even of geological science, we would mention the accumulated evidence which has been lately brought forward to prove, that the age of the human race, and the origin of the various arts and institutions which characterize man, are not more ancient than the Bible teaches. But to return to the subject in hand, we have no hesitation to describe the Wernerian theory as a system of general principles, more closely connected with facts, and explaining appearances much more satisfactorily than any other theory not strictly demonstrable,

The remark naturally recalls to mind the title of the Essay under our consideration, which respects" the important evidence in support of a theory of the earth, deducible either from its general structure, or from the changes produced on its surface by the operation of existing causes."-Dr. Kidd seems willing to avoid ranging himself under any particular leader on the subject of geognosy, but we can discover that although he is very polite and good-natured towards Dr. Hutton and Professor Playfair, he is not quite à decided Anti-Wernerian. His book, indeed, is chiefly occupied with remarks and objections which apply exclusively to the views of Werner; but we can perceive that his forbearance in another quarter, seems rather to imply neglect than coincidence of opinion. Nor do the objections of Professor Kidd direct themselves against the essential doctrines of the Wernerian school, but rather against some of their technicalities and nomenclature. He cannot see, for example, that the primitive rocks differ so much from those of the transition class as to justify the language in which they are described. He readily admits that the crystalline strata must have been precipitated from some medium containing their elementary parts in solution, and that, from granite to the red sandstone, all the rocks of the Werperian classification are in some measure connected. But the difficulty with our author is, that the particular series and order of succession detailed in books, do not always hold in nature, that there are many interruptions

and