sometimes occur at the junction of granite with gneiss, or clay slate.

4. The professor after admitting that there are granite veins frequently discovered which cannot be traced to any original mass or mountain, inform us, that "Dr. Hutton, from collateral evidence, conceives that these are always united to some granitic mass, though too deep, or at too great a distance to be traced and discovered." What, we beg leave to ask, is Dr. Hutton's evidence, either collateral or direct? It amounts, at the best, to mere conjecture, grounded too on a bold hypothesis, unwarranted by reason, and unsupported by observation. Such veins, we repeat, are contemporaneous, exactly like the siliceous and calcareous veins which present themselves in the most common rocks of the floetz formation, and which are to be seen on a still smaller scale, in almost all the members of the quartz and clay families. Our author is exceedingly unfortunate in all his examples under this head. He refers to Portsoy and Glentilt, to some of the Western isles of Scotland, particularly Tirce and Coll, as also some parts of Cornwall. Now, it happens that in Glentilt there is no granite at all, whilst the granitic veins at Portsoy can in general be traced to their termination, both above and below. Those again, of Tirce and Coll are evidently of the contemporaneous formation, the nature of which we have already described.

5. The account of Porphyry and Serpentine, in the opening of the third lecture is extremely meagre and unsatisfactory. Does Mr. Brande not know that the basis of porphyry may be claystone, hornstone, and pitchstone, as well as felspar? Is he certain, moreover, that he ever saw serpentine resting upon blocks of porphyry? And what are we to understand by the very loose expressions, "veins of granite associating with those of steatite, pervading the granite?" and "Serpentine at Portsoy associating with granite?" Such descriptions of the locality and relative situation of rocks, would not be pardoned in a common miner. Of limestone too, that very important mineral substance, all that we are told, with respect to its geognostic relations at least, is, that it is associated among primary rocks with mica-slate and serpentine, and that in "Inverary Park it may be seen in contact with micaslate and porphyry." After these enlightened and profound remarks, which constitute the philosophy of this part of the geological outlines, we are gravely informed, that "the most esteemed varieties (of marble) are perfectly white and free from veins, somewhat translucent, and susceptible of a good polish;" and that "these marbles are imported for ornamental purposes, especially for those of the sculptor," all which is followed by this simple assurance: "We have now considered a highly important series of rocks, and have enumerated their characters as insulated individuals."

To be serious: had this book been the first publication in the department of mineralogy; had Werner, and Kirwan, and Von

Busch, and Jameson, never written their several works; had the English public in these times had as few means of prosecuting this interesting study, as they possessed in the days of Burnet or Whiston, then, peradventure, might such a treatise as that now before us, have done some credit to its author, and some good, perhaps, to the inquisitive student. But, in the present state of knowledge, both as to simple minerals, and the composition and relation of mountain rocks, the case is, without doubt, entirely different, and these "Outlines of Geology," accordingly contain not, we are positively certain, one single fact or argument which is not already before the public in a more accurate and intelligible form. Considering what has been done by the Geological Society, the Wernerian society, by Dr. Kidd, and Professor Jameson, compared with the scanty and incorrect details of Mr. Brande, we cannot sufficiently condemn the imprudence of the writer, in the journal of the Royal Institution, who says, in allusion to the essay we are now reviewing, that "she (the Institution) boasts of the first attempt to describe the strata and mineral productions of Great Britain."-Nascitur ridiculus mus!

We had marked several other mistakes in the course of reading this little work, but we shall content ourselves with mentioning one more, namely, the appearance of sandstone, when in beds, alternating with trap rocks. In such circumstances it is very well known, the sandstone at the line of junction has an indurated look, as if a portion of the greenstone or basalt were incorporated with it, or introduced by percolation into its pores; and this appearance has been ascribed by the Huttonians to their favourite doctrine that the trap rocks were originally interjected between the sandstone beds in a state of fusion.

"The common observer," says Mr. Brande, "to whom a piece of basalt is presented, would presently announce it to be the produce of a volcano, and the analogy between it and lava is most striking. This alone would justify us in concluding that whinstone is the produce of fire. But the Huttonian hypothesis, as applied to its origin, becomes much more satisfactory, when we contemplate the effects produced upon the strata, into which it has been thrown, or upon the substances in its vicinity. Thus the sandstone of Salisbury Crag is broken, indurated, and even fused by its irruption."

In reply to this statement, we have briefly to observe, that the fusion of such sandstone is a mere fancy of Dr. Hutton's; the very same appearance being discoverable in sandstone, where it alternates with slate-clay, at a distance too from trap of every description, and even in situations where no trap is to be found.

These remarks naturally lead us to the second part of the subject discussed by our author, and introduce us to his notions on what has been called a theory of the earth. Taking up very literally the doctrines of Hutton and Playfair, he regards trap rocks, as well as granite, as having been completely melted in the immense subterranean fire, lighted up by his master, at an indefinite VOL. X.

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depth in the entrails of our globe, and afterwards thrown up to form masses, beds, and dykes among the stratified minerals deposited by the ocean, Let us examine then, into the few phenomena of which we are in possession, and see how this hypothesis accounts for the said fused sand tone of Salisbury Crag. Mr. Brande certainly does not require to be told, that in the wellknown hill he has mentioned, there is a succession of strata, or beds, of greenstone and sandstone alternating with each other; and this being the case, we are desirous to be informed how the fused trap could make its way through the sandstone mass, and divide it into regular strata, parallel to one another, and to the interposed beds of greenstone! It is admitted by all Huttonians, we believe, that sandstone is a deposition from water, and moreover, that it has never been melted in their mighty furnace at the centre of the earth; how then are they to explain the undeniable fact, that strata, composed of a stone, avowedly of aqueous origin, are found alternating with those of another stone, which they maintain to be of igneous origin, in the most regular succession, and preserving at the same time in their position the strictest parallelism throughout their whole extent. Could the melted greenstone be injected from the deep, in a direction nearly horizontal too, into a superincumbent rock, so regularly, and almost at given distances! We admit that the Wernerians have to encounter no small difficulty in explaining the alternation of sandstone and greenstone, in what they call their independent coal formations; and it is not very easy to conceive that the fluid which covered the face of the earth, should deposite siliceous matter in a state of mechanical division, until it had formed one stratum in a particular place, and then proceeded to deposite hornblende and felspar until it had formed a stratum of greenstone to cover that other stratum, and so on in regular succession, we know not how often. There is a difficulty here, and no candid Wernerian will deny it; but still, when compared with the monstrous assumption, that the one rock was spouted into the other from a great depth in a state of fluidity, it vanishes into nothing. If, however, the Huttonian could prove that, where the sandstone is found in contact with the trap, the former is indurated, or fused, in a way in which it is never found, when in contact with any other kind of rock, we should be compelled to yield to a presumption at least considerably in favour of his hypothesis. But so far is this from being the case, we are prepared, as we have already said, to bring forward a multitude of facts to show that sandstone exhibits the very same appearance; the appearance of induration, or fusion, we mean; where it alternates with slate clay, a substance which no man ever imagined to have been exposed to fire.

When on this topic, we may adduce one or two cases from Dr. Murray, whose book Mr. Brande does not appear to have read. Alluding to the operation of the internal heat of the Huttonians, the Doctor mentions, among other things, that strata of rock-salt

are sometimes covered by strata of sandstone or limestone. The Huttonian geologist, he observes, must suppose that this sandstone has been consolidated by the central heat, acting through the rock-salt below it. But this is plainly an impossibility. The salt is a substance comparatively very fusible, as it can even be volatilized by the heat of a coarse pottery furnace, while sandstone is very infusible. The heat necessary, therefore, to soften sandstone in this position, must have melted the salt beneath; and as this latter substance is of a much inferior specific gravity, the sandstone must have sunk in it, and the arrangement observed by nature could never have been produced. We find, continues the Doctor, in innumerable cases, strata more imperfectly consolidated than others above them, and of course further removed from the consolidating power, though the difference cannot be ascribed to any difference in the fusibility of the substances composing them. An example will place this in a clear light. In a section of the strata at Newcastle, coal is found at the depth of 102 feet; over it is a bed of black clay, 13 feet thick, with impressions of ferns in its substance; above this, another bed of harder clay, 26 feet in thickness. The stratum incumbent on this is a hard quartzose sandstone, with specks of mica, 25 feet thick; and this is again covered by clay. Now, how could this sandstone have been consolidated by the subterranean heat, while so many feet of clay beneath it, and of course, nearer the operation of that heat, had not even been indurated! We may pronounce it impossible that it should be so. Nor is the example uncommon: there are many similar to it, and even less favourable, as the banks of clay extend to eighty, an hundred, or more fathoms in thickness, with perfectly consolidated sandstone above; and this is diversified with alternations of limestone, gypsum, coal, and a great variety of other secondary rocks.

In this book of Mr. Brande's there is not the slightest attempt made to remove the objections now stated; indeed he does not seem to be aware that such objections have ever been urged. With regard, again, to the difficulty attending the fundamental position of the Huttonian hypothesis, that there exists a subterranean fire, which consolidates and raises mineral strata; the pabulum which maintains it, if it does feed upon consumable materials, the causes and periods of its renovation, if it is ever extinguished or suppressed; our author merely observes, that "the discoveries of Sir Humphrey Davy, concerning the true nature of earthy bodies, have furnished unexpected evidence in defence of these apparent, incongruities of the Huttonian doctrines." With the utmost desire. to appreciate the value of this evidence, we are entirely thrown out in our search for the particular point, on which it may be supposed to bear. That the alkaline earths have a metallic base of small specific gravity, and easily combustible, is a fact, the dis-, covery and confirmation of which we owe to Sir H. Davy; but as no attempt has been made to deduce from that fact, either that

lime or any other earth constitutes the burning substance in the centre of our globe, or that these bodies have become more combustible since their constituent parts were brought to light, by the analytic processes now attached, we cannot possibly discover the connexion to which Mr. Brande refers us, between the splendid experiments in the institution and the doctrines of the Huttonian theory. But, leaving professor Brande, who has not said any thing new, either for the theory which he has chosen to defend, or against that which it has pleased him to oppose, we cannot help observing, in relation to the Huttonian hypothesis, that its author has undertaken to explain, from an assumed and very doubtful principle, the most magnificent phenomena on the earth's surface. What an immense body of granite and other primary rocks must be contained in the Andes, and in the Thibet chain of mountains, the latter of which ascend nearly twenty-seven thousand feet above the level of the ocean! If the secondary strata, which rest upon the sides of those gigantic ridges were as the Huttonian maintains, at one time, a dead flat at the bottom of the sea, how incalculably large the quantity of matter, and how immeasurably great the force, necessary to raise and support them at such an elevation. Those astonishing chains of mountains which, as Cuvier says, constitute the frame-work of this globe, stretching from the arctic nearly to the antartic circle, and giving a form and character to all our continents, in the old world as well as in the new, originated, says the disciple of Dr. Hutton, in the spouting up of melted granite from the bowels of the earth! The mighty Andes themselves, towering into the clouds, and extending more than a thousand leagues in length, are to be traced to a Plutonic furnace, belching forth quartz and mica in a state of fusion!

A thought has just struck us, which, we imagine, might be applied with some success, to ascertain whether transitive and secondary rocks have been deposited, according to the Wernerian hypothesis, on the primitive masses, placed at their present height above the level of the waters, or whether, agreeably to the views of Hutton, they were broken and forced up from a horizontal position at the bottom of the sea. If the secondary strata, covering the sides of a primitive mountain would, when restored to their level posture, occupy more ground than the base of that mountain, we might justly infer that they had not been deposited in horizontal layers. If, for example, a mountain elevated four thousand feet above the ocean, presented on its sides, at the height of three thousand feet or upwards, a stratification of secondary rocks, we might safely conclude that these rocks had been deposited upon it, and not broken through and lifted up during its ascent from below; for, according to the latter supposition, the separated strata would not have attained so great an elevation. Something no doubt, depends upon the length of the base, and the angles at which the mountain rises from the plain, but in no case can the sum of the two sides, to the point at which they are over laid with secondary strata, exceed the base, without furnishing po