was at work at the time the shales in which they are imbedded were deposited, and before the overlying stratum was formed. Above this bed of shale we have a thin band of dark-grey stone (No. 19), varying from 1 inch to 3 inches in thickness, containing Pecten Valoniensis, Avicula contorta, Schizodus cloacinus, Modiola minima, and what appear to be worm-tracks, or casts of the traces of crawling mollusks or crustaceans. This stone band, the only one in the series where (owing to the indefatigable researches of my friend Mr. Waugh, of the Great Northern staff, to whom I owe the accurate diagrams accompanying this paper) I have met with the well-known Pecten Valoniensis, so common in other similar localities, lies just above the septarian nodules in the shales below, sometimes reclining on them; and where these bodies occur, the stone assumes, as just stated, a dome-shaped curve, being thinnest on the raised summit of the nodules, and thickest in the intervening spaces, while, resting on the stone, in the hollows between the swellings caused by the septaria, lie veins of black fibrous gypsum similar to those described in the shale-bed (No. 18) below. Next in order comes another bed of black fissile shale (No. 20) from 1 foot to 3 feet thick, similar in character to all the others, and forming the highest bed of the series in this locality, all above it being, as far as the railway-cutting extends, denuded and worn down by the drift, which, at a distance of about 90 yards above Lea-bridge, suddenly cuts clean through all the intervening beds down to the main stone band (No. 9), crushing and distorting the various strata, and making the smooth slippery surfaces of the shales appear as if they had been polished *. At this point also the strata from beneath rise again, and the grey Keuper marl becomes visible at the base of the cutting, showing the form of the Rhætic beds in 'this locality to be that of a shallow synclinal basin. That higher beds of the series existed in these parts is evident from the clean-fractured uneven fragments of White Lias which are found in the overlying drift, containing Myacites musculoides, Cardium Rhæticum, and other fossils, with the old perforated tubes of boring mollusks, the latter pointing, as Mr. Moore, in his paper already cited, observes, to a quiet period of deposition, when such delicate operations could take effect. One of the most remarkable characteristics of the Gainsborough beds is the presence of the immense quantity of iron pyrites found in the different strata, all of them, whether shale or stone, being literally filled with this mineral. In the shale it occurs as a simple cube, or number of cubes, and in the stone as a bright metallic layer or streak; and so filled is the entire series with this substance, that I have seen, after heavy rains, the sides of the cutting in places stained yellow, as if with rust, completely effacing the lines of bedding. How far the surface-limits of this Rhætic tract extend it is not easy to ascertain with exactness; judging, however, from the contour of the surrounding land, an estimate of its size and position may, I think,

Since this paper was read, I have discovered, in the old undisturbed parts of the cutting, traces of strata in situ belonging to the Rhætic series higher than those described.

with some degree of probability be made out; and I have endeavoured in the accompanying map, taken from the Ordnance Survey, to define them. To the east of the Triassic escarpment, extending from the Rhætic cutting at Lea northwards towards Gainsborough, the land lies in a gentle slope, rising again, though very slightly, at a distance of less than a mile on the average, with an outcrop of Liassic clays; and in the hollow between these ridges, judging from

Fig. 2.-Sketch Map showing the extent of the Rhotic Beds
near Gainsborough.

the direction of the dip, and the general trend of the land, it appeared to me likely that the Rhætic beds would be found on the surface; and hearing that a well had been dug in the line of this depression, near a farm-house marked on the map, about 3 miles north of the Lea-beds, I examined the earth thrown up, and found, as I anticipated, the various stones and shales of the Rhætic zone,

undiminished to all appearance in size and thickness, the main stone band and the other prominent strata, with their accompanying fossils and stock of pyrites, seeming all to be present as at Lea.

Taking the entire depression between the Keuper and Lias outcrops, and presuming it to be occupied with the Rhætic beds, as in all probability it is, we get an area of from 3 to 4 miles long, and from a mile to 2 miles broad, as the surface-extent of this northern deposit; but whatever its size may actually be now, there can be no doubt that it once formed part of the north-western boundary of a vast Rhætic sea, which extended, it may be, from Norway*, across the German Ocean, to Ireland, and southwards down the continent of Europe, and which, save in such patches as these, has long since been swept off the earth's surface, or buried beneath more modern deposits; and it is from such considerations, and the light the discovery of these outlying strata casts on what would otherwise be vague and obscure, that the interest and value of their examination mainly depend.

JUNE 5, 1867.

SPECIAL GENERAL MEETING.

The following addition to the Bye-laws was proposed by Mr. S. R. Pattison, seconded by Mr. J. W. Flower, and adopted by ballot, with one dissentient :

Section XIX. 5. The Society shall not and may not make any dividend, gift, division, or bonus in money, unto or between any of its members.

ORDINARY GENERAL MEETING.

Augustus Wollaston Franks, Esq., F.R.S., F.S.A., Keeper of Antiquities, British Museum, W.C., was elected a Fellow.

The following communications were read:-
:-

1. The ALPS and the HIMALAYAS: a GEOLOGICAL COMPARISON. By HENRY B. MEDLICOTT, Esq., A.B., F.G.S.

[The publication of this paper is postponed.]

(Abstract.)

CURRENT opinions on Alpine geology are first fully discussed by the author, especially as regards the abnormal nature of the actual boundary of the Molasse with the rocks of the higher Alps, including the explanation usually given of this phenomenon, and of the contortion of the inner zone of Molasse-namely, the direct upheaval of the main mountain-mass. Mr. Medlicott then describes some of the

*The probable existence of the Rhætic beds on the Island of Bornholm, and in the province of Schoonen, is indicated on Dittmar's map showing the distribution of the formation; but at present there is no fossil-evidence to prove with certainty the age of the beds in question.

sections exposed on the south flank of the Himalayas, and suggests a parallelism between them and those exhibited in the Alps. The clays, sands, and conglomerates of the Sivaliks are very like those of the Molasse; and in both regions the coarser deposits prevail towards the top. In the Himalayas also the younger Tertiary deposits almost invariably dip towards the mountain-range which they fringe, the plane of contact inclining in the same direction, and thus producing actual, though not parallel, superposition of the older rocks. All the arguments which have been used to prove prodigious faulting in the case of the Alps would therefore, the author states, be quite as applicable to that of the Himalayas. But, as regards the latter range, Mr. Medlicott brings forward evidence which appears to him sufficient to prove that the present contact of the Sivalik formation with the mountains is the original one, modified only by pressure, without relative vertical displacement; and that the sinking of the mountain-mass is the proximate cause of the contortions of the Tertiary strata. He then endeavours to show that this explanation is equally applicable to the Alps, especially as it seems also to account for collateral phenomena which appear difficult of explanation consistently with the ordinary hypothesis; and he concludes by discussing the current theories of the formation of lake-basins, in relation to the more immediate subject of his paper.

2. On some STRIKING INSTANCES of the TERMINAL CURVATURE of SLATY LAMINE in WEST SOMERSET. By D. MACKINTOSH, Esq., F.G.S.

1. Introduction.

CONTENTS.

2. Sections in a Quarry near Wiveliscombe.

3. Terminal Curvature of Lamina near Raleigh's Cross.

4. Transportation of Blocks.
5. Apparent Reversal of Dip near
Gupworthy.

6. Concluding Remarks.

1. Introduction.-During the last two years I have been making a series of observations in the West of England and in Wales, with the hope of being able to throw some fresh light on the relative nature and extent of oceanic and atmospheric denudation, and on the origin of superficial accumulations. In some parts of Siluria, during the spring of last year, I supposed I had met with a proof of tranquil marine deposition in horizontally arranged chips of slate resting on the edges of highly inclined laminæ, until I found that I had been looking on a continuation of these edges in a curved-back position, instead of seeing the curvature in profile.

In the autumn of 1866 I noticed several instances of the above phenomenon, which have not yet been described by geologists *. the nearly level floor of one of the valleys which indent the southern slope of the eastern part of the Quantock range of hills, I found the

* For an instance near Ashburton, noticed by Mr. Godwin-Austen, see Trans. Geol. Soc. 2nd series, part ii. vol. vi. p. 437.

laminæ of the Devonian (Carboniferous?) slate very regularly and distinctly bent or curved backwards, or towards the south. The idea of a more powerful agency than rain or frost then seemed to suggest itself; but it was not until I had examined more extensive sections further to the west, on the east Exmoor hills, that I became convinced of the necessity of having recourse to a more uniformly efficient cause than even the most exaggerated form of what is commonly called atmospheric action. The object of this paper, however, is not so much to theorize on the precise nature of this cause, as to state several important facts.

2. Sections in a Quarry near Wiveliscombe.-In a quarry about a mile and a half from Wiveliscombe several very instructive sections of the terminal curving-back of lamina are exposed. The slates (which have a southerly dip) appear to be very flexible; and this may be partly the reason why they have been so little broken. But the wonderful continuity of the curvature here exhibited must, I think, be partly due to an extreme uniformity in the movement. The bed of curved slates (represented in the figure), on the western Sections of curved lamina near Wiveliscombe.

side of the entrance to the quarry, is from three to four feet thick. The line of demarcation between the commencement of the curving back and the undisturbed mass of slates below is remarkably distinct and straight on looking along the strike of the cleavage; but on looking at nearly right angles to the strike, the surface formed by the edges of the laminæ beneath, though equally distinctly marked, is very uneven, as if the once superincumbent moving agent had exerted considerable inequality of pressure, so as to give rise to irregular grooves and ridges. The upper surface of the bed of curved laminæ, which is very uniform, is overlain by a layer, nearly two feet thick, of reddish loam, containing fragments of quartz &c. On the opposite side of the entrance to the quarry the curving back for some distance is on a nearly level plane. Here the bed of displaced laminæ is from two to three feet thick. It exhibits a double curvature, approaching the shape of the letter S. Over it there is a layer of about two feet of loam, with many quartz fragments, chiefly angular, but occasionally a little rounded.

3. Terminal Curvature of Lamina near Raleigh's Cross.-There are several facts connected with the foregoing sections which obviously point to a powerful and uniformly operating cause; but the belief in such a cause becomes irresistible as one surveys the nume