the coal basins in South Britain are found. A considerable track of country in the midland counties of England and South Wales is occupied by a red sand-stone formation, which agrees remarkably with the characters of the old red sand-stone of Werner. On this sand-stone several, if not all the coal-fields of South Britain, rest. In the neighbourhood of this tract the older formations are in many places to be seen, as in the range of the Malvern Hills, between Herefordshire and Worcestershire. Beginning from these hills, we easily trace the succession of rocks from the primitive to the newest floetz strata. I shall briefly mention the most important rocks which this series contains in this part of England.

The Malvern Hills, of which Mr. Horner has given an account, forin a small range running nearly from N. to S. They consist chiefly of granite and syenite, in which no stratification can be discovered, perhaps on account of their being very much concealed by soil. On the western side of them, beds of a very hard compact lime-stone lie against the feet of the hills dipping towards the west. In conformable position with these, and frequently alternating with them, are beds of a clay rock, which varies in its appearance. In some places it is a hard slate, and contains scales of mica in great abundance; in others it becomes a mere shale. These rocks contain a profusion of organic remains, particularly encrinites, madreporites, and terebratulites. Mr. Horner's account of them is minute and accurate: I only mention them for the sake of remarking their position with respect to the red sand-stone, which I have traced, and which appears to fix their place in the geological series. Mr. Horner considered these rocks as belonging to the transition formation. In this opinion he was right, if, as it appears scarcely to be doubted, the sand-stone is the old red sand-stone.

As we approach these hills from Ross, we perceive that the country which lies to the S. W. of the range is occupied by a suc cession of low ridges lying nearly parallel to the direction of the Malvern Hills. Most of the observations which Saussure made of the calcareous chains of the Alps are here verified in miniature. The ridges generally turn their abrupt sides towards the primitive range, and slope on the other side. They consist of the lime-stone and clay rock above mentioned, the beds of which generally dip towards the W. and S. W.; but at the northern extremity of several ridges they turn round the hills, and dip northward. In the most westerly of these ridges, near Fownhope, about 13 miles in a direct line from the Malvern Hills, the clay and lime-stone rock dips at an angle of about 60° towards the S. W. Here we lose this formation.

Immediately after passing over this western limit of the limestone, we find the red sand-stone above-mentioned lying upon it, and in a position exactly conformable with it. The sand-stone forms low ranges of hills parallel to the former. It dips to the S.W. at a considerable angle, which diminishes as we recede from the

lime-stone. It runs hence through the greatest part of Herefordshire, generally preserving the same direction and dip.* It passes into Shropshire, where, from Mr. Aikin's observations, it appears to pass under the coal-fields. It forms a great part of Cheshire ; and, according to Mr. Aikin, contains the salt springs of Droitwich, &c. and the salt deposit of Northwich.t I have followed it into Brecknockshire and Monmouthshire. The lime-stones which shut in the coal-fields every where lie upon it. These I shall denominate mountain lime-stones, for the sake of distinction. They may be traced from a few miles S. of Ross to Chepstow, forming the beautiful cliffs which overhang the Wye, and in a conformable position with the subjacent sand-stone, dipping to the S.W. In general the sand-stone consists of fine grains of quartz, with a little argil, and a variable quantity of oxide of iron and mica: but in the hills, and on approaching the lime-stone, its constituents are differently disposed. At the bottom of a hill we often find the common red sand-stone; higher up, a stratum of pudding-stone, containing rounded pieces of quartz, large masses of which in loose blocks cover the declivities; then there are beds of a whitish stone, the iron and mica disappearing, which makes a good building stone, but near these there is a thin bed consisting almost wholly of oxide of iron, and others almost entirely of mica. All these varieties occur in a hill near Ross, called Herol Hill. On the top of it the mountain lime-stone appears; and about a hundred yards further a pit is open, when the lowest bed of the forest coal rises near to the surface of the ground.

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This red sand-stone formation is concealed near the Severn by the red marl rock and the Lyas lime-stone; but it appears again near Bristol, forming the basis on which the Somersetshire coal basin rests, of which Mr. Gilby has given an excellent account in the Philosophical Magazine for last November. I have seen it lying under the lime-stone near Axbridge, at the southern edge of this basin. This formation would appear every where to rest upon the

* Mr. Horner considered the Malvern Hills as affording countenance to the Huttonian theory. He observes, that the position of the stratified rocks seems to indicate that they were lifted up by a force from beneath. But if he had traversed the country to the westward of these hills, he would have found that the strata have generally a similar position, and even dip at a much greater angle, at the distance of 12 or 14 miles from the Malvern Hills. The absence of the stratified rocks on the eastern side may be accounted for by supposing that a submarine current flowed down the present Vale of Severn at the era when the rocks in question were deposited. Many indications may be found of the existence of such a cutrent; but if none could be produced, surely the hypothesis is fully as admissible as the ejection of the granite masses from the abyss of Tartarus.

+ It is very strange that, after all that has been said concerning this salt formation, we are yet without any satisfactory account of the stratum in which it occurs. Dr. Holland, in the first volume of the Geological Transactions, says, that it is subordinate to the sand stone of the independent coal formation. Mr. Aikin, in the same volume, informs us that they belong to the old red sand-stone; and Mr. Horner, as 1 perceive by the abstract of his late memoir on the southeastern part of Somersetshire, given in the last number of the Annals, assigas them to the newer argillaceous sand-stone termed red marl.

transition rocks. I have mentioned its relation to those near Malvern. Mr. Aikin informs us that it rests, in Shropshire on highly elevated strata of grey-wacke; and I observe, by the last number of your Annals, that Mr. Horner has found it lying on the same formation near the Quantock Hills, in Somersetshire.

The red sand-stone is supposed to contain no organic remains. I believe, however, that I have seen traces of entrochites in it. The mountain lime-stone which rests upon it contains the fossils enumerated above, and which agree so remarkably with those of the transition formation. It often resembles the transition lime-stone in its texture, but is less crystalline, and has much thicker beds.*

From these considerations I think it is evident that the rocks belonging to the independent coal formation follow the old red sandstone in the geological succession, and are more ancient than any other member of the floetz series.

But further, we may almost venture to assert that the succeeding formations in the system of Werner have no existence in this country, and that the order of floetz rocks, from the old red sand-stone up to the chalk which form the greater part of South Britain, bear very little analogy to the succession pointed out by that celebrated naturalist.

I have stated that the strata above-mentioned dip most commonly towards the S. W. The coal, together with the micaceous sandstone and the argillaceous stone which forms the roofs, &c. of the coal seams, dip conformably; but this, as well as the general inclition of the subjacent rock, is subject to variations. The whole commonly incline at a very perceptible angle. Over these rocks are deposited a series of strata which lie very nearly parallel to the plane of the horizon.

The first or lowest of these is that which Messrs. Townsend and Farey denominate red ground and red marl. It has, if I mistake not, been confounded with the old red sand-stone. Its composition varies; sometimes it is an argillaceous sand-stone, but without mica, and destitute of that slaty form which characterizes the older sand-stone. I never saw it contain any rounded pieces of quartz. In some places it becomes a marl rock, consisting chiefly of carbonate of lime. This is the case on the banks of the Severn, where it contains a bed of gypsum.† According to Mr. Townsend, the

*This resemblance accounts for the disagreement we find among high authorities on the subject of these lime-stones. Mr. Werner, in his little book on veins, mentions the lime-stone rocks at the peak in Derbyshire twice: once he calls them transition rocks, and once affirms that they are floetz. M. Brochant says they are transition, and I understand that Mr. Jameson considers them as floetz.

+ I scarcely need observe that I have not mentioned these strata for the sake of claiming the discovery of them, but merely with the view of making some remarks on their order, and the relation which their succession bears to the series of M. Werner. A very accurate account of these formations is already before the public, in the paper of Mr. Gilby above referred to; and an extensive collection of interesting facts respecting these and other newer floetz rocks in South Britain is contained in the work of the Rev. I. Townsend, who mentions that he derived, bis first information concerning them from Mr. W. Smith.

magnesian lime-stone of Derbyshire and the North of England belongs to this formation.

Above this is the Lyas lime-stone enclosed in a bed of clay. This stratum abounds in shells. In this respect it agrees with the second floetz lime-stone of Werner, which is called in Germany muschel kalkstein. It contains pentacrinites, which are considered as peculiar to this stratum. I have, however, found them in the oolite rock in Gloucestershire, but the Lyas is their proper abode, and they gradually disappear in the succeeding formations. It is here also that those large heads and bones are discovered which have been supposed to be the relics of crocodiles. They are of several species. The remains which Mr. Johnson, of Bristol, has collected, proves that some of them at least belong to an unknown marine animal. From the account which M. Cuvier has given of the cliff at Honfleur, containing the remains of crocodiles, I think it is highly probable that it belongs to the Lyas stratum. He mentions two species which nearly resemble the gavial. If any of your correspondents has seen the rock at Honfleur, and will favour us with an account of it, which may enable us to ascertain its identity with the Lyas lime-stone rock, it will throw an additional interest on these remains. All the other fossils occurring in this stratum are oceanic, among which are ammonites often three feet in diameter.

The Lyas formation is very extensive in South Britain. It is well known at Lyme and Chasmouth on the south coast, and traverses the island towards the German Ocean. I have been informed that it occurs in Anglesea.

Above the Lyas is the extensive calcareous formation containing the oolite or roestone. This cannot be, on account of its position, the roogenstein of Werner, which is subordinate to the second sandstone, and therefore below the muschel kalkstein.

Above this several other rocks are enumerated by Mr. Townsend, which I have not traced. Over these is the upper stratum of sandstone, which supports the chalk formation.

On the whole, I think it appears that there is very little conformity between the floetz series of Werner and that which occurs in South Britain; but the older formations, as far as they are yet known, coincide with his system. We may observe that the travellers, who in distant regions of the earth have been so powerfully struck with the conformity of geological phenomena with the observations of the Saxon Professor, as Humboldt and Von Buch, have chiefly directed their attention to the older formations. I am not aware that any disciple of the Freyberg school has detected the succession of floetz rocks, as detailed by Werner, beyond the limits: of Germany.

But if we are to admit any reasons grounded on speculative geology, an universal conformity in the primitive and transition formations is quite as much as can be expected. At the period of the deposition of the last, the waters of the ocean are supposed by

Werner to have subsided, and to have formed separate basins or seas. The subsequent deposits must have varied according to local circumstances. Therefore some variety in the succession of floetz rocks rather confirms than invalidates the Wernerian theory of the earth. I have the honour to be, Sir,

Sketch of a General Theory of the Intellectual Functions of Man and Animals, given in reply to Drs. Cross and Leach. By Alexander Walker.*

SIR,

(To Dr. Thomson.)

In the 26th number of your Annals of Philosophy, was announced a discovery of the use of the cerebellum and spinal marrow by Dr. Cross;-in the 27th number, Dr. Leach stated "that the same facts, or facts that lead to similar conclusions, were published in Lettres de Hufeland à Portal, 1807, and Anatomie du Systême Nerveux, &c. par Gall et Spurzheim ;-in the 28th number, I, conceiving that Dr. Leach meant to ascribe these discoveries to Gall and Spurzheim, denied that they were contained in the work referred to; +-and in the 29th number, Dr. Leach says, "Permit me, Sir, to assure you that the letter from Hufeland to Portal contains precisely the same opinion respecting the use of the cerebellum as that given by Mr. Alexander Walker and Dr. Cross; but he there adds, that he had quoted Gall and Spurzheim's work only as stating these opinions to be erroneous; and, while he asserts that my anatomical and physiological statements are " inaccurate, suppositious, and at variance with nature," he gives the results of his own recent examinations"-the conclusions which he draws after having" carefully examined the structure of the spinal mass of nerves." §

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* Though this communication is rather too long for the Annals of Philosophy, we have given it a place, that every one of the Gentlemen concerned in this dispute may be upon a footing; but as the object of the Annals of Philosophy is not controversy, the Editor trusts that they will see the propriety of letting this subject rest where it is.-T.

✦ Certainly when a Gentleman has said “that facts which lead to similar conclusions were published" in a particular work, meaning thereby to give them priority over another statement, it is most natural to suppose that such was the original source of these facts; and, at all events, the conclusion is unavoidable that they are there considered as facts-the term which Dr. Leach employs. Annals of Philosophy, vol. v. p. 346.

Ibid. p. 345,