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more than micaceous and argillaceous sandstones altered by heat; and certainly, in their mode of stratification and lamination, they correspond most exactly. Granular quartz may have been derived from siliceous sandstone, compact quartz from the same. Clay-slate may be altered shale, and shale appears to be clay which has been subjected to great pressure. Granular marble has probably originated in the form of ordinary limestone, having in many instances been replete with shells and corals now obliterated, while calcareous sands and marls have been changed into impure crystalline limestones.'...
' Associated with the rocks termed primary, we meet with anthracite, just as we find beds of coal in sedimentary formations; and we know that, in the vicinity of some trap-dykes, coal is converted into anthracite.'--pp. 288-9.
In accordance with this theory, Mr. Lyell, giving the name of hypogene to the class of rocks formerly called primary-(the latter term being rejected as conveying a false notion of their age, while the former correctly expresses their leading character, namely formation below the surface of the earth and he separates this class into two divisions—the Plutonic, or unstratified, and the Metamorphic, or altered stratified rocks.
Our author enters into very little detail in explanation or support of this metamorphic theory, which is rather thrown out by hiin as a suggestion than insisted upon as capable of demonstration, We are certainly no converts to it as yet. The main argument in its favour is the stratification or rather laminated structure of these rocks, gneiss, mica and clay-slates, Sic. But besides that their mode of stratification is not very similar to that of the secondary sandstones, shales, and marls, from which they are said to be formed, it would seem to us, that the liquefaction and alteration by volcanic heat, which are supposed to have effaced all traces of organic remains in them, would equally or still more effectually have obliterated their lines of stratification, which in secondary sandstones, marls, &c. are very evanescent. Now, we believe it may be affirmed as a general fact, that the degree of lamination presented by the rocks in question is in direct proportion to the quantity and more or less parallel disposition of that extremely lamellar mineral, mica, which is disseminated through them. Their lamipar structure seems clearly to be owing to the abundance and parallelism of the plates of mica they contain. But Mr. Lyell's theory supposes all this mica to have crystallized where it occurs, since the rock assumed its laminated structure; in other words, that the effect preceded its obvious cause.
We do not wish to advance any rival theory of our own, but content ourselves with observing, that, if the stratification of these rocks prove them to partake of a sedimentary character, it is such
as might be expected to proceed from the subsidence of the crystalline minerals they are at present composed of, viz., mica, quartz, felspar, &c. from a body of agitated and perhaps intensely-heated water, in which these substances, the materials, be it recollected, of the contemporaneous plutonic rocks, were suspended. If we imagine a mass of granite to be forcibly protruded at the bottom of a deep sea, at an intense temperature, the tremendous conflict that must ensue between the two elements may be supposed to occasion such agitation and turbulence in the contiguous waters as would disintegrate and sweep off much of the superficial granite, to be deposited in calmer spots around the scene of conflict, and, as the eruption subsided, upon its site. The result would be some rocks very like gneiss, in the immediate neighbourhood of the erupted granite; mica-slate at a little distance, where the filmy plates of mica subsided in abundance; and clay-slate at a greater distance, where the finer particles, which would remain longest in suspension, at length sank to the bottom. The heat of the water would retain much of the quartz in solution, and account for the half-worn, half-unelted character which its grains and nodules exhibit in these rocks. If Mr. Lyell will recollect his own relation of the extreme difficulty of distinguishing some of the tertiary sandstone of the edges of the Limague basin, from the gneiss and granite of whose disintegrate materials it consists, and into which it actually seems to graduate, he will see that there is no occasion for imagining the crystals of a stratified granite to have been formed subsequently to its deposition. That the intense heat under which the rocks in question were produced powerfully affected their character, we have no doubt.
They may have been also more or less modified by it subsequently, though this we see no reason for concluding. The friction they have sustained during their elevation from the depths in which they were formed, we cannot but think likely to have still further influenced their peculiar structure. No rocks are so twisted or folded into such intricate curves as these, and their flexures and contortions are usually the greater, the greater the quantity of mica they contain. Now this peculiarly texible and lamellar mineral, the plates of which slide with great ease upon one another, must, where it abounded, have conferred a proportionate flexibility and internal mobility of particles to the laminæ of the rock, inducing it to yield readily to the squeezes it was subjected to under enormous conflicting and irregular pressures, and to be drawn out into those long lamellar folds which characterize these rocks, mica-slate especially; and which are perhaps quite as much owing to this internal movement as to their original subsidence in
parallel parallel flakes from aqueous suspension. In some of the pearlstone lavas, which no one can suspect to be sedimentary, internal friction of this kind has given rise to just the appearance which characterizes gneiss-—the disintegrated crystals of felspar, mica, and hornblende, being drawn out in lengthened stripes and layers, in the direction of the motion communicated to the mass.
Let Mr. Lyell imagine sedimentary beds of the disintegrated materials of granite to be formed at the bottom of a deep ocean, under the circumstances we have described, and subsequently ex: posed to intense pressure and internal motion, as they were gradually thrust upwards to their present situation, and perhaps be will allow that the resulting rocks must partake very much of the character of his metamorphic class. We throw this hint out for his consideration, against the time which, we are sure, cannot be far distant, when a new edition will be required of his work.
Mr. Lyell winds up his book by a defence from the charge which he considers us to have brought against him on a former occasion,* of endeavouring to establish the proposition, that the existing causes of change have operated with absolute uniformity from all eternity. The unfairness of the charge, he observes, was pointed out by Playfair, who said, ' that it was one thing to declare that we had not yet discovered the traces of a beginning, and another to deny that the earth ever had a beginning.' Now had Mr. Lyell contented himself with declaring, that we had not yet discovered traces of a beginning to the present general condition of the world, we should have found no fault with the tendency of his argument, though we might have disputed its correctness. But he went farther, and declared it to be unphilosophical to look for traces of a beginning, or to imagine it possible that we should discover such.
We argued, that as the different states of the earth's surface, and the different species by which it has been inhabited, have all had their origin, and many of them their termination, so the entire series may have commenced at a certain period—that, as we admit the creation of man to have occurred at a comparatively modern epoch-so also we may conceive the first creation of the planet itself; that, as astronomy has proved this planet to be a mere speck in the immensity of space, so geology may prove that, like the mineral and organic forms and species it contains, it has had a beginning, and will probably therefore have an end.
Mr. Lyell, admitting the weight of this reasoning, still contends, that though it may strengthen our conviction, that the present system of change has not gone on from all eternity, it cannot war* Quarterly Review, No. LXXXVI., p. 464, Oct. 1830.
rant us in presuming that we may be permitted to behold the signs of the earth's origin, or the evidence of the first introduction into it of organic beings '- that “to assume that the evidence of the beginning or end of so vast a scheme as is comprehended in this globe, with all its animate and inanimate contents, lies within the reach of our philosophical inquiries, or even of our speculations, appears to be inconsistent with a just estimate of the relations which subsist between the finite powers of man and the attributes of an infinite and eternal Being.'
Undoubtedly, we should not be warranted in assuming that we have discovered, or shall ever discover and identify, the firstformed strata; but we may surely seek for them without irreverence. If we believed in Mr. Lyell's subterranean cookery of sedimentary strata into granite, we should consider the search hopeless one; but certainly no more a profane inquiry into hidden mysteries than any one of Mr. Lyell's own speculations. To an
eternal and infinite Being,' the countless ages through which Mr. Lyell traces back the history of the earth are but as one day-the globe, with all that it inherits, is but as a point in the space occupied by his works. His attributes' are not degraded, but rather exalted, by the supposition that, at his fiat, new worlds, arrayed in gorgeous beauty and teeming with wondrous contrivances, are called into existence; while others, in turn, decay and become extinct. Such an idea is in no way inconsistent with the perfect harmony of design and unity of pupose,' which is exemplitied in all we have yet been permitted to know of the universal creation. We must retort then upon Mr. Lyell himself the charge of unwarranted assumption which he has levelled at us, though in the same friendly spirit in which he has met our remarks. We must aver, that 'to assume that the evidence of any beginning or end to the present state of the globe we inhabit, lies without the reach of our philosophical speculations, is inconsistent with a just estimate of our own powers and of the attributes of the eternal and infinite Creator.'
The practical difference between ourselves and our author is simply upon the question, whether or not there are traces on the earth's surface of former changes of a more violent and tumultuary character than such as habitually occur at present— whether the present order of change is cyclical, and uniform in amount through equal periods, or progressive and, on the whole, diminishing in violence. The latter supposition does not, we before remarked, involve any doubt (as Mr. Lyell seems to imagine) of the permanency of the existing laws of nature. The theory, for example, of the gradual refrigeration of the globe does not sup
pose any fornier deviation from the existing laws of heat, light, or gravity. Mr. Lyell mistakes the essential character of his own argument. It is not the constancy of the laws of nature which he is contending for; this no one disputes. His real theory is, that there has been no progressive variation in the intensity of the forces which modify the earth's crust—but that a cyclical succession of such changes, of equal amount in equal periods, has been going on throughout all time, so far as geology enables us to explore its abysses. And on this point Mr. Lyell must be content to join issue with other geologists, under the disadvantage of all analogy being against him : from which, as we have shown, it is presumable, à priori, that the series of geological mutations to which the earth is subject, is a progressive, not a stationary or recurring 'series—that our planet, like every individual form within it, is subject to the law of integration and disintegration, has had a beginning, and will have an end..
We have deemed it due to Mr. Lyell to express fairly our opinion on this topic; but it is not less due to him than to our readers, that we should observe, in conclusion, how distinctly the general tendency of these volumes is to open up new, interesting, and expansive views of the mighty work of Creative Intelligence. The work is, in this respect, a fit prelude to the Bridgewater Treatise on Geology, which we are expecting from the pen of Dr. Buckland. Though not, like the latter treatise, devoted spe. cially to their illustration, no reader can peruse it without being deeply impressed by the fresh and striking proofs it affords, in every page, of the Almighty Power, Wisdom, and Goodnessproofs, multiplied through countless ages of the globe's history, equally conspicuous in the microscopic fossil and the inassive mountain-chain, in the falling rain-drop as in the swelling ocean, in the destroying agency of the volcano and earthquake no less than in the luxuriant productiveness of the animal and vegetable kingdoms, whose limits both in duration and extent have been so indefinitely enlarged by the discoveries of modern geology.
n the falling microscopic fossithe globe's his
Art. VII.-The Georgian Era: Memoirs of the most Eminent
Persons who have flourished in Great Britain from the Acces-
as opened in the preface, is plausible :-first the editor proposes to exhibit in one view the eminent men who have flourished