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sary for determining this question have not, that we know of, been made at St Michael's Mount: but they have been made in other places; and the fact has been found to be as last represented. This is true of the granite veins near New Galloway, of which, as Dr Berger remarks, Sir James Hall caused a model to be constructed.
• How comes it,' says Dr B., if the origin of these veins • is to be ascribed to the action of a force from below, that they
occur in so few places ? and how comes it that the grauwacke,
as it approaches the junction between it and the primitive rock, . continues diminishing in thickness ?' * To these two questions, we believe, it would be easy for a Huttonian geologist to reply ;-in the mean time, we must observe, that the Doctor passes, in profound silence, over the obvious objections to his own hypothesis. In particular, he does not attempt to explain how such a number of thin plates of granite, as the veins at St Michael's Mount are supposed to consist of, were formed on the surface of a rock without any mould in which they could be cast, and how they remained projecting from that surface, without any support, from the time of the formation of the granite to that of the transition rocks.
Dr B. is of opinion, that the granite of Cornwall is not stratified ; and he thinks, that true granite is never found possessing that character. • The opinion,' says he, that granite is stra"tified, is one which I cannot adopt, even after having visited " those places where Saussure thought he had discovered the
strongest proofs in favour of it.' : In this opinion we are very much disposed to acquiesce; and we think it is valuable, in such a case, to have the judgment of one who has examined granitic rocks in such various situations, and particularly those in which their disposition into strata was thought to be most clearly ascertained.
The observations, made in the course of this survey, on the inclination and bearing of the strata, are less numerous and pre'cise than might have been expected. The kilas is, in generel, represented as lying conformably on the granite on both sides of the main ridge. This, however, we believe, is not universal;---and, if we are not misinformed, is sometimes in vertical beds transverse to the ridge just mentioned. In one instance, Dr B. takes notice of a fact that is very much of this *kind ;--that though, on the south slope of the mountain chain of Cornwall, the strata of killas dip S. S. E., near Mount's Bay they dip N. N. W.--that is to say, they dip towards the granite, and instead of being laid upon its slope, or placed conformably, as it is called, are abutted against it.
In speaking of the mines, the Doctor observes, that Werner has brought forward so many facts, in support of the two fundamental positions, that veins have been originally open fissures, and that they have been filled from above, that this theory scarcely receives a greater degree of stability by any of the further proofs which are daily discovered. We readily admit, that the first of these positions is very well established ;-the proofs of the other seem to us extremely inconclusive-founded, as they are, upon that string of unsupported postulata which was taken notice of in a former Number of our Journal, and which we believe to be nearly unexampled in any work that presumes to consider itself in the light of a theory founded on experience and observation.—The question concerning the minerals that have come from above, and those that have come from below, is
easily resolved :-it must require a patient and candid examination; and, above all things, a determination to resist eveту evidence not founded on the most strict analogy, or the most rigorous induction. The fact which the Doctor adduces of pebbles, found in a mineral vein 250 feet below the surface, is certainly in point; but, in strictness, it only proves, that veins were open fissures, (which nobody presumes to deny); and that some of the materials that fill thein may occasionally have fallen in from the top.
On the direction of the veins in Cornwall, he remarks that the productive veins extend from E. S. E. to W. N. W. Some of the veins penetrate to a great depth,--such as 140 and 180 fathoms; and in passing from one species of rock to another, they generally change their degree of richness.
There are other veins which intersect the former nearly at right angles, and are called cross-courses. Some of the most consideraible of these extend from sea to sea; and, as the Doctor says, consist of marl or clay. But, if we mistake not, there
are among these cross veins, some that contain copper, and that are in all respects mineral veins. The veins of granite and porphyry are also in the number of the cross-courses. They are evidently of posterior formation to the former, which they generally disturb and turn out of their course at the points of intersection.
The mines of Cornwall are very numerous; and it appears, that, in the year 1800, the number wrought was not less than 99. Of these, 45 were copper—28 tin–18 copper and tin–2 lead1 lead and silver--1 copper and silver-1 silver-1 copper and cobalt-1 tin and cobalt—and 1 antimony. To these may be added some mines of manganese, which were not worked when this enumeration was made. (p. 167.)
With the exception of platina, mercury, molybdena, and the five bodies so little known and apparently so little useful, tellureum, tantalium, columbium, and cerium, Cornwall affords indications of all the metals.
On the whole, this paper, though with some defeets as a mis neral survey, contains a great deal of valuable information, and manifests in the author much diligence and research. We cannot help thinking, that the Wernerian geology is faulty, in directing the attention of the mineral surveyor to some favourite points, and withdrawing it from the rest. The order in which the strata succeed, seems to be the great ohject to which the mineralogists of that school are inclined to attend; and the order fixed on by Werner being very precise and very different, we imagine, from that which nature has adopted, the person who would reconcile the one with the other has abundance of work upon his hands. The junction of the rocks with one another, particularly of the stratified with the unstratified, their inclina: tion to the horizon, the line in which they intersect it, the space which strata of a particular kind occupy, and the heights to which they ascend, -these, as well as the mineralogical characters, ought to be diligently examined.
The use Dr B. has made of the barometer, we think extreme ly laudable; and we hope, that an. instrument, calculated to give such valuable information, not only concerning the mountains themşelves, but the position of particular minerals, will, by and by, be considered as an essential part of a geological apparatus. The compass for measuring the bearings of the
strata, and the dinometer * for estimating their dip, are still more importants and we regret to find them so rarely employed in the present survey. A map of Cornwall, with the points marked where particular observations were made, would have added much to the value of this communication.
Dr Berger, as a foreigner, has a claim to indulgence ;-and being, perhaps, not quite familiar with our language, he might, when his knowledge depended on the information of others, be occasionally deceived. It adds much to the value of his observations, that his eye has been accustomed to the sight of rocks and of mountains, where they appear on the greatest scale, and in their noblest forms. He has been trained to the scia ence he pursues, among the Alps of Switzerland; and, born in a land of liberty and independence, he has taken refuge in the
only * A very ingenious instrument, contrived by the Right Honourable - Lord Webb Seymour, for measuring at once both the inclina. tion and the bearing of any stratum,
only country where they now exist ;--and where he hopes that the girdle of the ocean, and the spirit of the people, are a security against that oppression which the bulwark of his native mountains was unable to resist.
A very interesting paper on the mineralogy of Shropshire, by Arthur Aikin esq., is the eighth in this collection.
It seems that a vertical section through the Wrekin, in the direction of west by north, and east by south, intersects the great coal field of Shropshire, on the east side of the mountain, and two smaller formations of the same mineral on the west. The former lyes between the base of the Wrekin, and a branch of the old red sandstone; which, proceeding southwards from the great body of that röck, which occupies so large a portion of Cheshire and the country to the north, divides the coal fields of Shropshire and Staffordshire from one another. Against this sandstone, the coal field first mentioned seems to abut, on the east side, dipping towards it at an angle of about 6o. Under the coal lyes a body of limestone strata, dipping also toward the red sandstone.
The coal formation is composed of the usual series of rocks, which are most completely seen at the Madeley coalery, where a pit is sunk to the depth of 729 feet, through 86 beds, which compose the whole of the formation.
The first 30 strata are composed of sandstone, fine grained, with mica, and thin plates of coal.' The 31st and 33d are coarse grained sandstone, remarkable for being penetrated by petroleum. They are together 15 feet thick, with a bed of sandy slate clay, 4 feet thick, interposed between them. These are what furnish the petroleum spring'at Coalport.
The first coal forms the 9th bed from the surface, at the depthi of 102 feet, and is not more than 4 inches thick. The first bed that is worked, is a five feet coal, at the depth of 490 feet, But the greatest deposit of coal is lower down, consisting of 9 beds, the aggregate thickness of which is about 16 feet. The rock upon which the coal formation rests, is for the most part limestone, which is nearly horizontal at the eastern extremity of the above section, but rises, with a considerable elevation, as it approaches the high country about the Wrekin. There are two fractures in these beds, that run parallel to one another; and on the west side of them the limestone beds are more eleyated thanı on the east. It would seem, from Mr Aikin's description, that there is no decisive character contained in the rocks themselves, by which it can be determined whether this is to be ascribed to the forcible elevation of the strata at one end, or their depression at the other. There is another range of limestone, farther to
the west, and parallel to the former. It is very full of tubulites, and other coralline remains. In this limestone, the elevated portion has an intimate connexion with an unstratified greenstone, which lyes under it, at the point where it is most elevated.
An important geological question here occurs. Are these beds, or are they not, in the position in which they were first deposited ? That they are not in that position, appears to be supported by the impossibility of a bed of sandstone being deposited on a plane at an elevation of between 30° and 40°, in such a manner as to constitute an extensive stratum of an uniform thickness. The position, also, of the tubulites, which pierce through the marl, is a subsidiary argument of no small weight. These tubes, some of which are scarce an eighth of an inch in diameter, with a length of twelve inches, are perpendicular to the plane of the stratum ; and therefore, when that plane makes an angle of 40° with the horizon, the coralline tubes must make with it an angle of 50°, a situation not at all agreeable to the class of animals to which they belong, as they always affect a vertical position. It remains to discover, whether, in this body of rock, the elevation of one end, or the depression of the other, is most probable. The former supposition seems to derive great probability from this, that where the beds of limestone and sandstone are most elevated, a great mass of greenstone lyes immediately under them. Is it not, therefore, probable, says Mr Aikin, that the greenstone has occupied the situation • which it now holds, posteriorly to the formation of the strati
fied rocks between which it is at present found ? But though • the above facts,' adds he, 'should be considered as justifying « the hypothesis of the active agency of the greenstone, and
consequently its fluidity, I am by no means prepared to affirm • that this fluidity was that of igneous fusion; for neither the
sandstone, nor the limestone, nor even the crumbling clayey
mar, appear to me to have undergone the smallest alteration • by the contact, or close vicinity of the greenstone.'
The section, as it proceeds to the westward, encounters the grauwacke, elevated towards the north-west, at an angle of 50°; over which lye the strata of red sandstone, elevated at an angle of 10° towards the north-east. These two kinds of strata, there fore, make with one another an angle which it would require a trigonometrical calculation to determine, from the data which Mr Aikin has given, but which may be nearly taken at 59°; which, therefore, is the angle which the sandstone makes with the grauwacke. At Welbach, near the western extremity, is a patch of coal strata, contained in a hollow between the grauwacke