ART. IV.-An Introduction to Geology: comprising the Elements of the Science, in its present advanced state, and all the recent Discoveries; with an Outline of the Geology of England and Wales. By ROBERT BAKEWELL. London:Third Edition, entirely recomposed, and greatly enlarged. With new Plates. First American Edition, edited by PROFESSOR SILLIMAN, of Yale College, with an Appendix, containing an Outline of his Course of Lectures on Geology. New-Haven: Hezekiah Howe. 1829.

It seems to be a very common opinion, that the study of geo logy is dull, dry and unattractive to all but the initiated inquirer, who has contrived to get enthusiastic in a kind of knowledge, which, to the generality of men, presents a lowering and repulsive aspect. We have too much respect for people's understandings, to consider this as the effect of any thing else, but erroneous impressions regarding the true nature and objects of geology. We can hardly pity the wiseacre more, who could travel from Dan to Beersheba, and cry "all is barren," than he who can catch but a single glimpse of the whole truths, the grand and interesting views, which this science unfolds to man, and declare that it is unworthy of employing the thoughts of any but the plodder in science, whose dull conceptions are only enlivened by the discovery of a rock, or the analysis of a mineral. If vigorous and extensive research, bold, deep, and original philosophy, enlarged and sublime views-all connected with the earth we inhabit, and in no small measure, with the nature and history of its living occupants, in times past as well as the present-have any thing in them to engage the active spirit of man, geology advances claims to our attention too numerous and strong to be easily set aside. And judging from the connexions which some branches of knowledge have with the popular feeling, we have no fear that these claims will not be admitted, when once thoroughly and clearly understood. We hear every day of the sublime and elevated discoveries made by astronomy; of the glorious mechanism which the anatomist, with palpable distinctness, places before our eyes; and of the charms of that pleasing science which unrobes to our sight the internal economy and rich garniture of the vegetable world. The former is concerned with other worlds, and the laws which bind them together; the latter, with the countless forms of being which enliven the surface of our own; while geology, without yielding to these in the high and noble character of its inquiries, shows us the worlds which have been, and traces the terrible revolutions of nature, which from time to time have "rolled them together as a scroll," leaving behind a few dumb but eloquent memorials, to convey to coming ages the story of their exVOL. VI.-No. 11.

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istence. Like the ghosts of the guilty dead which passed before the eyes of Dante in the infernal regions, the shadowy forms, not of men, but of ages, pass and repass in measured procession, before the steady gaze of the geologist, while he marks their characters and reads their history.

Geology carries us back to the very rudiments of our earthly habitation, while its scattered materials are yet destitute of form or consistence, and thence traces it upward through its successive approaches to order and beauty. The primeval ocean rolls its shoreless waters before us, loaded with the uncombined elements of the crust of our planet, which, by the union of combustibles, the evolution of gases, the precipitation of mineral compounds, and the play of innumerable affinities, are gradually moulded into shape, and become known unto men by various names. The thunder of the earthquake and volcano reverberates through subterranean caverns, upheaving the rocky framework of the earth into towering masses, destined to become the nucleus of future continents and islands. The different strata are deposited in successive series, the sea retires to its deepest basins, and dry land emerges from the bosom of the waters. The springs of life are now opened, and countless zoophytes, with other creatures of simple grade and marine origin, float in the sea, or adhere to the rocks, while luxuriant forms of vegetation cover the surface of the newly made soil. Fresh-water lakes, and marshes of large extent, diversify the land, furnishing an abode in their oozy beds, for zoophytes and numerous shell-fish, and supporting an abundant vegetation on their shores. In the lapse of time, these fill up, and give origin to vast formations of coal, with trunks of palms, and ferns, dispersed through their strata. Various limestones, slates, sandstones, and clay, are next deposited, coeval with a higher and more singular order of creation. Innumerable fishes people the lakes, and crocodiles, with lizard reptiles and enormous turtles, swim on their surface and sport on their banks. Here indeed we behold the Reptile class in its full development, displaying the most varied forms and gigantic proportions. Plesiosauri darting forth their long, swan-like necks to seize upon their prey, and Megalosauri rivalling the whale in length, paddle their huge forms with inconceivable rapidity through the waters. Gigantic Iguanodons, having their heads garnished with horns, and elephantine grinders in their jaws, repose in groves of palms and arborescent ferns; and winged lizards, realizing the fabulous creations of antiquity, are safely borne upon the breeze. But these extraordinary and gigantic beings, the beginning and the end of their order, are doomed to pass away, and with the deposition of the chalk formation, they have utterly disappeared. The wide-spread mantle of destruction is destined, in the fulfilment of time, to be once more raised, and new scenes of beauty and life are opened over

the face of nature. Marine mammifers, dolphins, lamantins, and morses now range through the seas, and numerous pachydermes, of novel construction, and gigantic size, characterize the animal population of the dry land. The Tapir-like Palæotherium roams over the plains, browsing on the tender branches of trees, and the Anoplotherium, like the Rhinoceros of our own day, plunges his unwieldy form into the lakes and rivers, and feeds on the roots and succulent plants that grow upon their banks. Again the scene changes,-"the winding sheets of nature" are drawn over the face of the earth, and these singular beings are erased for ever from the book of life. On the deposits which enclose their relics, extensive plains, crowned with rich vegetation, are again formed, to be the abode of still another creation of beings. Pachyderms still predominate in this new population; but gigantic pachyderms, elephants, rhinoceroses, mastodons, megatheriums, and hippopotami, accompanied by innumerable horses and many great ruminants. Carnivora, of the size of the lion, tiger, and hyena, desolated this new animal kingdom, which resembled, even in the extreme north, and on the borders of the frozen ocean of the present time, that presented to us only by the torrid zone. These too are overwhelmed in their turn, and give place to the condition of things which we now behold.

Such are the scenes continually presented to the view of the geological inquirer, and we can hardly conceive that they should lose any of their interest with those whose minds are open to the majesty and wonder of nature's works.

The name of this science is no doubt associated in the minds of many, with fanciful theories and idle speculation. There was indeed a time, when philosophers, forgetting the true limits of all human inquiry, had no other concern with the past condition of this terrestrial sphere, than to penetrate into the secret of its origin; and in the absence of any safe documents to guide them to their conclusions, they shaped their course by the loosest analogies, or what was still worse, assumed the existence of laws altogether different from those with which experience or calculation makes us acquainted. Imagination readily furnished the outlines of the picture, and no facts were too irrelevant or scanty, no views too partial, and no reasoning too shallow, to fill up the lights and shades, and give to the whole, form, distinctness, and the appearance of reality. Beginning, as they did, at the wrong end in their inquiries, it is no wonder that every subsequent step carried them still deeper into the maze of uncertainty and error into which they had entered. But we do not imagine that these speculations possessed a very pernicious tendency, as theories in the sciences generally have, for they were too remotely connected with practical inquiries to give them a wrong direction, and obtained too limited a belief to distort the observations of the

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generality of minds. So plausible did each and all of them seem to men of warm fancies and superficial habits of thinking, and so nicely balanced were their respective merits, that they were continually supplanting one another, and thus counteracting the mischief which, individually and unfollowed by others, they would probably have occasioned. Few, we suspect, have entertained any other than a poetical belief in the analogy that has been sometimes found between the structure of our globe, and the organization of the animal body; and the parade of comets, suns, oceans, and all the other supernatural machinery that has been pompously made to account for the production of our planet, has oftener led men to smile at the dreams of philosophy, than acknowledge the power of sound and logical reasoning. These speculations might be true or false, but none could be proved, nor was it of the slightest importance that they should.

The mischievous effects of theories under certain circumstances is no good argument, however, in favour of their entire exclusion from the sciences; for apart from the use which they have in giving system, spirit, and object to our researches, there is a pride connected with a belief in them, which, when it is generally understood that the only proof of their truth is facts, stimulates the mind to higher exertions, and thus becomes the means of increasing indefinitely our stock of really valuable knowledge. We have yet to be convinced that geological theories have not, on the whole, had a beneficial, rather than an injurious tendency, by leading to rigorous and extensive investigations, and adding to the mass of facts, on which, as a common basis, they must all repose. Few, we believe, will deny that it is to the discussions and investigations that have arisen from the rival theories of Werner and Hutton, that we owe some of the most valuable truths in geology, and much of the certainty and precision which characterize its present results. What was it but a strong and impelling desire to strengthen the claims of the latter of these theories, which led to the production of one of the noblest contributions to geological knowledge, the Illustrations of Playfair? Thus, however remote from the truth a theory may be, it never is entirely without its use, for the facts on which it pretends to be based, lose none of their value by being applied to wrong purposes, and are always ready to the hand of subsequent inquirers, who may make them subservient to more substantial conclusions.

The rage for world making has now subsided; geologists have become not only ashamed of trying their hand at such empty follies, but lastingly convinced that their rightful province is to examine the various materials which constitute the crust of the earth, to ascertain the relations which they bear to one another, and discuss such other questions as these inquiries may naturally sug

gest. If we can judge of the times aright, geologists of the present day are decidedly averse to mere speculation, and resolutely discountenance it wherever it appears; and if all others were as little addicted to unwarranted assumptions and hasty generalizations, we cannot help thinking that the sciences would be all the better for it. Not that they are utterly devoid of theoretical views, and make observations purely for the pleasure of recording them; for the understanding invariably shoots ahead of simple observations, and endeavours to deduce from them some general principles; and the certainty of this process, when not conducted by experiment or calculation, must always vary with its subject. What we mean is, that theoretical views are not ostentatiously thrust forward as objects of the first importance, but on the contrary, are considered rather in the light of humble and rational conjectures, pretending to nothing more than an approximation to the truth. We have been thus particular on this point, because so long as the impression is abroad, that geology is merely a bundle of fancies, the conceits of warm-headed men, it would be idle to insist on its importance, or its claims to more general attention.

Another objection to this science is often mentioned, which it may be well to consider for a moment, since with the higher order of minds it undoubtedly has no inconsiderable weight,—it is the jarring and dissension which pervade its discussions, and the general uncertainty of its conclusions. Why should we plunge into a labyrinth of conflicting theories, incompatible observations, and contradictory results, to come out at last as wise as we entered? This objection has been greatly magnified by reason of the erroneous conceptions which are too commonly entertained respecting the nature of geology, and of course will appear very differently when the science shall be more clearly and fairly estimated. If we were inclined to start a paradox on the occasion, we should say that this is a striking proof how thoroughly and decidedly geology is a science of facts. Considering the small number of these which have been collected, in comparison with the almost inexhaustible source whence they are drawn, it is not surprising at all, that it is sometimes difficult to reconcile them one with another, and that our general principles are open to the serious charge of being derived from partial views of the facts. We are willing to let every man generalize according to the materials at his command, confident that as knowledge advances, these generalizations are easily modified or even entirely dismissed. What is doubt and confusion now, may be clearness and certainty at no distant period. Geological discussions are gradually eliciting the truth; and considering the infancy of the science and the immense range of inquiry which it embraces, it seems strange indeed that it should present so little obscurity and lack of certain