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mittee, for their kind assistance in making the arrangements for the meeting.

The following communications were then made to the Society :—

ON THE DISTURBANCES IN THE DISTRICT OP THE VALLEY OF THE DON.

BY REV. WM. THORP, OF WOMERSLEY.

Upon the last visit of the Society to , I had the pleasure of describing some of the geological features of the neighbouring district, and particularly those of the country between and Sheffield. I have again taken the liberty of giving a brief mining notice of the disturbances of the same district, because they are not only of such enor­ mous magnitude as to be of great interest to the geologist, but a knowledge of them is necessary to the successful min­ ing operations of that neighbourhood. Upon the former occasion, it was contended by one party that not only were the strata on the North side of the Don elevated above those of the South side, to the amount of 600 yards in vertical height; but that also there had been a horizontal lateral movement of the beds of the North side, in an eastward direction, to the length of five or six miles.^

* The proofs then adduced in support of a lateral movement were—1. That the various beds come from the North, up to the edge of the valley of the Don, but do not preserve their Northerly and Southerly direction across the valley, but are found several miles to the West; e. g.^the Silkstone coal ranges to Dropping Well, near Kimberworth, and is not found at the same depth until we arrive six miles West, at SheflSeld town. 2. A sudden variation in the direction of the water levels, from North and South to East and West, down the valley of the Don. 3. A fault, of exactly fifty yards, in the ironstone at Tankersley Park, running North and South; and another fault in the same ironstone, in Tinsley Park, [ten miles distant,) running in the same direction, and being i)f the same amount, were supposed to be one and the same fault, before the lateral traction Downloaded from http://pygs.lyellcollection.org/ by guest on September 28, 2021

I hope, however, now to be able to prove—1. That there is no vertical elevation of the beds of the whole country, on the North side of the valley of the Don, or, that the pre­ viously described elevation is merely local;—2. That the supposed lateral movement is due, in reality, to a depres­ sion or synclinal axis of the beds on the South side. It is, indeed, true that there is a vertical elevation, in the beds of the North side, over those of the South, if you com­ mence at Iccles Hall, and trace any of the deeper beds as far only as Keppel's Column ; but, in this case, part only of the disturbed country is described. These disturbances ex" tend over a much greater tract of country than is generally supposed : for instance, in the Thick coal they commence on the borders of , and extend as far as Elsecar; so that the whole country from Orgrave, near , and perhaps beyond it, to Elsecar, North of Wentworth House, is disturbed by variable and sudden inclinations of strata to the horizon, by one synclinal, and probably two anticlinal axes, and is more or less broken by faults of considerable magnitude ;—similarly, the disturbances commence in the Sheffield coal. North of Moor, and terminate only at Chapel Town ; and in the Gannister, at Dore, three or four miles on the South side of Dronfield, and terminate only at Deep Car; but beyond the tw^o points where each of these beds first becomes regular, or assumes its usual inclination to the West, there is indeed no material elevation of one side of the country above the other. In order to prove this, it is only necessary to ascertain the diiference in elevation above the sea, or between each took place. The proofs in support of a vertical movement were, the abrupt rise of all the beds to the North, between Rotherham and Sheffield; accompanied with several faults, which elevate the beds to the North, both of which are seen in Mr. Chambers' Works, at the Holmes, and on the line of the Sheffield and Rotherham Railway, These are further explained in the sequel. Downloaded from http://pygs.lyellcollection.org/ by guest on September 28, 2021

6

other, of any of the same beds, at the two points where the disturbances cease, on a North and South magnetic line. I shall, therefore, take one of the uppermost beds in the series, and one of the lowest—i. e., the Thick coal at Orgrave, on the edge of Derbyshire, and the same bed at Elsecar ; and the Grannister, or Pecten coal, at Dore Moor, in Derbyshire, and the same at Deep Car. Now the fall of level on the surface, from Elsecar to Swinton, is 67 feet, or 22^ yards, and the fall from Orgreave, on the North Midland Railway, to Kilnhuret, is not more than forty yards, and probably less; so the difference in point of level can only amount to eighteen yards. Again, the Gannister or Pecten coal, at Dore Moor, from barometrical observations made by me, in 1838, is 48 yards above the river Sheaf, at Hunter's Lane Bar; and Deep Car, through which passes the Manchester and Sheffield Railway, with a gradient of five yards to the mile, being eight miles distant, will give forty yards of ele­ vation above Sheffield ; so that the difference of elevation between the same coal at Dore Moor and at Deep Car, will only amount to a few yards. Thus, there is no material difference, in level, of the Thick coal, which, in the scale of strata, is a higher bed ; and, similarly, in the lowest worked bed, the Gannister. There is, therefore, no material elevation in the country on the North, above the same beds on the South side of the valley of the Don ; the intervening disturbances, therefore, are merely local, and have no gene­ ral effect upon the stratification of the whole country. I now proceed to shew that the supposed lateral movement is due to a depression of the beds on the South side of the Don. The water levels* on each side of the disturbed dis-

* A water level is a line at right angles to the steepest inclination of the coal, and is correctly represented by the spouts which carry water in any street; if the roofs of the houses rise due West, the direction of the street will be North and South, and the line of spouting, or water level, will be the same. A change of direction, therefore, in the water level, merely indicates an azimuthal change of the inclination of the coal-bed. Downloaded from http://pygs.lyellcollection.org/ by guest on September 28, 2021

trict run due North and South, by the compass ; but, in the distracted country, the beds rise more to the South, and the levels change to 23° and 28° to the West of North ; now, by this southerly rise, there is communicated to the dis­ turbed beds a dip of one yard in 20 or 25, in the due North and South direction^ ; so that, from Beighton to the turn or axis where the beds rise North, by the change of level alone, any single bed will be 150 yards deeper (supposing the sur­ face level.) This southerly rise is proved by the extensive water levels in the Sheffield coal, which, at Birley Moor, the most southerly point of the Sheffield Coal Company's workings, run due North and South, magnetic ; but, upon coming further North, the levels change to 23° West of North ; they are two miles in length, and, upon the colliery map, are semicircular. Again, the due North and South line from Orgreave runs over Brinsworth to Jordan Dam ; Brins- worth is equi-distant from the two places, and stands upon the red rock of Rotherham. Now it is most certain that the Thick coal at this place has sulFered an enormous depression, and that Brinsworth stands over the bottom of a synclinal trough ; for the Thick coal is here 350 yards deept, while at Orgrave pit it is 120 yards, the surface at Brinsworth being 18 yards higher. From Orgreave to Brinsworth, then, the Thick coal is depressed, either by dislocations or the va­ riation of level, or by both, to the amount of 200 yards at least. From Jordan Dam, a place near the Sheffield and Rotherham Railway, the same bed is depressed in an oppo-

* These beds rise 1 yard in 7. At an angle of \5o, or half between the level and steepest iLclination, 1 in 14; at an angle of 30°, I in 21, which last is nearly the direction of the Tinsley Park and High Hazles Levels. In fact, the rapid rise of strata, of 1 in 7, would of itself lead to the supposition that the whole beds were irregular.

t The four foot coal is 140 yards under the red rock of Kotherham, which is here 30 to 40 yards thick. The High Hazles Coal is 80 yards under the four- foot coal; and the thick coal 91 yards under the latter. Downloaded from http://pygs.lyellcollection.org/ by guest on September 28, 2021

8 site direction, south towards Brinsworth, but to a greater amount, for the Thick coal appears on the railway rising at a very acute angle to the North. The exact amount of de­ pression will be 350 yards, minus the diflPerence of surface level between Brinsworth and Jordan Dam. A very fine natural section is next exhibited in the cutting of the North Midland Railway, under Treeton; the beds are rising ra­ pidly to the South, from the red rock, opposite Catcliffe, to the High Hazles coal, at Swallow Nest; and in the last southward cutting, through the Red rock, there is a fault which, if the coal in the cutting is the four-foot bed, will not be less than 140 yards, producing an elevation to the South, or depression of red rock, which, from this point, ranges up to Brinsworth. Again, the same eiFects are exhi­ bited, in the lower beds in the Gannister, East of Dore and , which is rising rapidly to the South. At Binging- law Bar, the Hallam coal is seen similarly disposed ; so that, a little to the North of the present pits, it is covered by the third gritstone, from which slates are there dug. The same depression is proved by a consideration of the position of the High Hazles coal; its basset is seen opposite Beighton, at the bottom of the hill ascending to Swallow Nest, a place li mile South of Treeton; the place of basset being a quar­ ter of a mile on the East side of the North Midland Rail­ way ; but the same bed is 260 yards deep, at Brinsworth, and is worked at some depth near High Hazles, a long way to the west of Swallow Nest. In like manner, the North Midland Railway, about half a mile South of Beighton, crosses over the basset edge of the Thick coal, and then rests upon inferior strata. The depression, therefore, of beds from the south, or the southern axis of the synclinal, is proved, 1st, by a section in the Sheffield coal ; 2ndly, by one in the Thick coal; 3rdly, by that of the North Midland Railway, under Treeton; 4thly, by that of the Gannister or Pecten coal; 5thly, by that of the Hallam coal, at Ringing- Downloaded from http://pygs.lyellcollection.org/ by guest on September 28, 2021

9 low Bar ; 6thly, by a consideration of the position of the High Hazles coal, at Swallow Nest; and 7thly, by the Thick coal South of Beighton, and the situation of this coal with regard to the railway, and the general workings of this bed. The northern axis of the synclinal, or depression from the North, is well known ; it may be traced accurately in the workings of the Park Gate coal. Commencing at Keppel's column, this bed dips to the South, at an angle of 17° for 400 yards, to a throw of 125 yards ; it then dips at an angle of 28°, and afterwards at an angle of 32°, across therailw^ay, down to the axis. But Keppel's column is also the centre of an anticlinal axis ; for this coal dips rapidly to the North, from this point, down to the Old Park Gate Pit, on Thorp Common, and is there 44 yards deep ; the bearing of this pit from the column is 24° West of North (magnetic.) Again, the Northern axis is well exhibited in the flagstone which appears at Shirecliffe Hall, above ; but from hence the flagstone dips North to Bridge, and here forms a shallow synclinal; from which places it rises to and Wharncliffe Lodge, and finally dips away ra­ pidly to the level of the river Don, at Deep Car, forming one sjmclinal and two anticlinals. The Gannister from Moor dips to Hunter's Lane Bar, where it becomes 130 yards deep, under the flagstone ; batCrookes Moor is the centre of another anticlinal, for the Gannister is next seen at a much lower level, at , and thence ranging up to Stamiington; from Malin Bridge, it rises rapidly North, through Wadsley, to Owen's Moor; and then dips North to Deep Car, forming, in its course from Crookes, one synclinal and two anticlinal axes. The levels in the Thick coal indi­ cate, in addition to the northerly rise, several variations in the inclination ; beginning, on the North, at Stubbing, to Upper Hough, they run 4° "West of North ; South of Upper Hough, they run North 10° West, then change to 40.° East Downloaded from http://pygs.lyellcollection.org/ by guest on September 28, 2021

10 of North ; and the South level from the pit is 50° North of West; but from the termination of the Northern rise, at Stubbing, the lower red rock dips rapidly North, by the old whin-cover, towards West Melton. So that Stubbing forms the centre of another anticlinal, similar to that of Keppel's Column, Shirecliffe Hall, Wharncliffe Lodge, Crookes Moor, and Owen's Moor ; the effects of which are to reduce all the various beds elevated by the Northern axis* of the synclinal of the Don, to their original level. But this depression, or great synclinal trough, over Brins- worth, Tinsley Park, up to Bent's or Bench Green, produces a false appearance of a lateral movement; and first, from Der­ byshire, in the Thick coal. On the North Midland Kailway, about half a mile South-East of Beighton, the Thick coal is basseted out on the surface; but its western basset is pro­ longed as far as Handsworth, by Damall, to , where it is 4A) yards deep ; and if the inclination of the strata over this tract had been less than 1 in 7, its basset would have extended West of Sheffield; and that this coal has not been kept below the surface by the rise of ground from Beighton, is plain, for there is no difference of level between Beighton and AttercliiFe, as proved by the two railways ; while the coal is on the surface, at the place be­ fore mentioned, near Beighton, while it is 44) yards deep three miles to the West, at Attercliffe. This prolongation o^ the coal to the West affords an appearance as if the coal had been drawn laterally backwards three miles from Attercliffe, down to the East of Beighton. 2ndly, half a mile West ol Mosbro', in Derbyshire, is the outcrop of the Sheffield coal ;

* The highest elevation of the beds, by this axis, as at Keppel's Column, Crookes Moor, Shirecliffe Hall, &c,, is from 200 to 280 yards aboye the same beds, as elevated by the Southern axis of the synclinal, as at Orgrave, Dore Moor, &c. It would be of great use to the Society to ascertain how far these disturbances extend to the West. They seem to terminate to the East, near Rotherham, and are connected with some great faults which run North and South. Downloaded from http://pygs.lyellcollection.org/ by guest on September 28, 2021

11 but this outcrop is continued by , North of , to St. John's Church, in Sheffield ; and the extension of this coal so much to the West produces a ficticious appearance, as if it had suffered lateral traction, to the amount of four miles, to Mosbro', near Eckington. The same appearances are exhibited in the Gannister or Pecten coal, from Beau- chief Abbey to Bench Green. In like manner, on the North side of the Don, the Thick coal is worked at Rawmarsh, and much at the same depth at Attercliffe, and appears here to have been drawn back four miles. Again, the Sheffield coal at Dropping-Well near Kimberworth, is worked much at the same depth as in Sheffield Park, and exhibits an appearance as if it had suffered lateral traction to the amount of six miles. But both the appearance of a lateral movement of the beds on the Derbyshire side, just mentioned, and also that on the North side of the Don, is merely owing to the depression or synclinal axis above described ; and, as an effect of this depression, an extension of the disturbed beds to the West, beyond their general range, phenomena which are ex­ hibited in every East and West fault, where the downcast beds are always prolonged in their outcrops to the West. There is, however, this to be observed, that the beds of the Northern axis of the synclinal of the Don are elevated more abruptly, and to a higher level, than those on the opposite side, (as observed in the note,) and, as a conse­ quence, have suffered denudation to a greater amount; and their basset edges are driven back further than those on the Derbyshire side of the axis. There is, therefore, no lateral movement of beds on either side of the Don; neither is the country on the North side vertically ele­ vated 600 yards above that on the South side, maintain­ ing that elevation, as was stated at a previous meeting. In fine, the whole phenomena are well described by a writer in the Magazine of Natural History, and quoted in the Arcana v2 Downloaded from http://pygs.lyellcollection.org/ by guest on September 28, 2021

12 of Sciences for 1838 :—" Along the Westerly edge of the " coal measures, there are well-known irregularities, occa- " sioned by elevations and depressions, across the general " range of the series, causing sinuosities in the marginal " edges of the coal fields. The lands Eastward, over the " ridge contract, and those Westward, in the hollows, expand " the width of the coal measures; so that the first rise, in " the North side of the Dun, causes a vacant space between " Sheffield and Chapel Town; and the second rise, South of " Sheffield, and in Derbyshire, causes a vacant space in the " productive coal measures between the high part of Shef- " field Park and Coal Aston; and in the hollow between " these two ridges, the coal is thrown forward under Shef- " field. But there is a greater Westward receding (projec- " tion) in the Dronfield trough, one side of which, rising to " the North, causes a long East and West range through " Coal Aston." Mr. HABTOP said, Mr. Thorp had observed that he stated on a former occasion that the strata North of the Dun were elevated. What he contended was, that either those on the North had been elevated, or those on the South had been depressed ; but he never gave a positive opinion, further than as to the fact that there w^as a difference in the level of the strata on the two sides of the valley, of nearly 700 yards. Geologists found much difficulty from the want of a suf­ ficiently correct map, shewing the bearing of the minerals ; and probably considerable discrepancies would be found be­ tween the map he produced and that of Mr. Thorp. He should confine himself to the facts he had ascertained from his own observations ; and he thought, if the information of the different members could be collected on a map on a large scale, it would greatly increase the usefulness of the Society. He then proceeded to make some remarks on the Thick coal, which was worked at Beighton, at Handsworth, at Attercliffe Common, at Masbro', and at Earl Fitzwilliam's Downloaded from http://pygs.lyellcollection.org/ by guest on September 28, 2021

13 colliery at Rawmarsh ; pointing out the changes in the depth of the coal at these places, and in the direction of the water levels; that while the general direction of the water levels, both to the North and South of the valley of the Don, was from N.W. to S.E., yet, in the valley, for five miles, the direction of the water levels was at right angles to their ge­ neral course, viz., from N.E. to S.W. Mr. Hartop illustrated his remarks by a map of his own, constructed some years ago, for the purpose of laying down the water levels of the different collieries, and he thought it would be very useful if this were made a leading feature in geological maps, in mineral districts. Mr. MoBTON said, the Society had several times been favoured with explanations of the geology of the Don valley. Indeed, it had become a sort of standing subject, but unfor­ tunately there were not two explanations alike. The arguments advanced to-day by Mr. Thorp to prove the existence of a synclinal axis were certainly novel, and, he thought, philosophical, and in accordance with facts. Mr. Morton's own observations of the geological structure of the country between Leeds and Chesterfield, led him to coincide with Mr. Thorp's views. From Billingley to Leeds, the strata rise to the North and North-West, but from Rother- ham to Chesterfield they rise to the Southward; and the inference is, that the measures between Billingley and Rotherham lie in the bottom of a deep hollow or depression, which, in fact, is Mr. Thorp's synclinal axis. Mr. Hartop, on former occasions, had endeavoured to shew that a lateral movement of the strata had taken place towards the East *, but the evidence was not sufficiently strong to satisfy him (Mr. Morton) that such was the case. From the commencement of the Society's discussions on this subject, Mr. Morton had always considered that the geological phenomena of the Don valley could be explained by the supposed intervention of a large fault, which had Downloaded from http://pygs.lyellcollection.org/ by guest on September 28, 2021

14 considerably uplifted the measures on the North side of the river; and if this elevation were proved, all the other ap­ pearances could be shewn to have resulted from violent denuding causes, that had operated over a considerable sur­ face of country Northward. But Mr. Thorp had adduced facts to-day which disproved the upraising of the strata on the North side only, and demonstrated that an elevation existed on both sides; for he stated that the difference of level be­ tween the Thick coal at Orgreaves, near Hands worth, and the same coal at Elsecar, was only 18 yards, although its depression under Attercliflfe common was considerable. Sup­ posing Mr. Thorp's barometrical measurements and other data to be correct, the conclusion to be drawn was, either that the strata in the valley of the Don had sunk down, or that the strata on the North and South sides of it had risen up several hundred feet, forming a synclinal axis in the vicinity of the river; and Mr. Morton considered this theory more rational, and more in accordance with facts, than any other theory that had hitherto been advanced. The appearances most difficult to explain are local; they are seen in the immediate vicinity of the river between Shef­ field and Botherham ; and they are such as to render an in­ telligible description on paper almost impossible. Plans and sections give but a very unsatisfactory explanation of the great and sudden turn in the direction of the basset edges of the Coal measures in this district, and it is only by a model of the country, like Mr. Sopwith's model of the Forest of Dean, that its very curious and interesting geolo­ gical features can be fully exhibited. Mr. HABTOP thought the slight difference in the level of the strata at those points proved nothing at all. He should not have been surprised had the difference been much less, when the length and the fall of the streams from each point were taken into account, both of which meet in the river Don at Conisbro'. As to there being a basin or trough, he Downloaded from http://pygs.lyellcollection.org/ by guest on September 28, 2021

15 thought there was no intimation of anything of the kind ; for by reference to the map, it would at once be seen that the Thick coal,Avhich it was now contended w^as on the same level at Handsworth and at Elsecar, would, if it had conti­ nued in its usual course from Handsworth, have been 700 yards deeper when on the line of " rise" opposite Elsecar; or if traced from Elsecar, would have been found so much higher than it is to the " deep" of Handsworth. Mr. THORP, in reply, then said, that he should not have brought this subject again before the Society, had he not thought that our reputation as geologists would be affected by the imperfect state in which we left our inquiries, at the former meeting at Sheffield, upon the disturbances of the Don. Upon that occasion, it was maintained that the whole country on the North side of the Don, from Sheffield to Rotherham, had not only been horizontally drawn back five miles, but also elevated vertically 700 yards. He thought that he had now proved that neither the one movement nor the other had taken place. Mr. Hartop (with whom before was Professor Johnston) seems now to abandon as untenable the lateral movement, for he has said nothing upon the sub­ ject, except that the water levels change their course at right angles down the line of the Don. But a change in the di­ rection of a water level merely indicates a change in the "rise," or azimuthal inclination of the coal bed, a common occurrence in every coal field, and it is not the least evidence of any lateral movement. Besides, if there is a lateral movement at all, there are two lateral movements, one on each side of the river Don, drawing the Thick coal from Attercliffe, on the South side, back to Beighton; and on the North side, the same coal to Rawmarsh; but to suppose any such movements is perfectly absurd. Mr. Hartop, however, yet contends for the vertical elevation of one side of the Don over the other to the amount of 700 yards. And no doubt this is correct locally, or if a short North and South section Downloaded from http://pygs.lyellcollection.org/ by guest on September 28, 2021

16

be taken, (for instance, from Iccles Hall, or any place conti­ guous to the river, and prolonged as far only as Keppel's column,) but then part only of the disturbed district is passed over; and because he had Studied, and yet recommends to be studied, only the small tract of country adjoining the river, and not rather to consider the general effect which these enormous disturbances have upon the disposition of the strata of the whole country, it hence arose that we all left the former discussion of the subject, under the erro­ neous impression that the whole country was elevated to the above amount, and maintained that elevation Northwards through Yorkshire, which has been proved perfectly incor­ rect in the paper, by an inquiry into the difference of eleva­ tion above the sea of the same coal at Elsecar, near Went- worth House, and atOrgreave, on the borders of Derbyshire. Mr. Hartop, however, yet thinks that " the slight difference in level proved nothing at all;" but it proved everything which he (Mr. Thorp) required, viz., that the vertical ele­ vation of 700 yards is only local, and that there is no verti­ cal elevation of the beds of the whole country on the North side of the Don above those of the South. But Mr. Hartop still says, that " as to there being a basin or trough, he thought that there was no intimation of anything of the kind." Now, that there is a South side of the basin, or rise of beds to the South, has been proved in my paper by—1st, a section in the Sheffield coal; 2nd, by one in the Thick coal; 3rd, by that of the North Midland Kailway ; 4th, by that of the Gannister and Pecten coal; 5th, by that of the Hallam coal; 6th, by a consideration of the position of the High Hazles coal, at Swallow Nest and at High Hazles; 7th, by that also of the Thick coal at Beighton and at Atter- cliffe, and its position with regard to the two railways. And that there is a North side of the basin, or rise of beds to the North, has been proved—1st, by a sight of the beds any­ where on the Sheffield and Rotherham Railway; 2nd, by a Downloaded from http://pygs.lyellcollection.org/ by guest on September 28, 2021

17 section in the Park Grate coal; 3rd, by one of the flagstone; 4th, by that of the Grannister and Pecten coal; 5th, by one of the Thick coal. If any single one of these sections be correct, it would be sufficient to prove that there exists a trough or basin ; but I have produced seven sections shew­ ing a rise to the South in seven different localities, and five shewing a rise to the North; and yet Mr. Hartop, without attempting to disprove the correctness of any one section, contents himself by asserting that he thinks there is no inti­ mation of anything of the kind I Mr. Hartop is also in error when speaking of the Thick coal as at Handsworth and Elsecar. The North and South magnetic line from Elsecar reaches Orgreave by Lord Fitzwilliam's large map, and the coal at these two points is nearly at the same elevation above the sea, or any other fixed point; but the water levels of Hands worth, as now worked, range N. 25 W., and point to the Flagstone at Grenoside, as proved by Mr. W. Jeffcock and himself (Mr. T.,) and if prolonged, would ultimately go in that direction West of all coal beds in Yorkshire. And to suppose the Thick coal continued in its usual course from Handsworth, where it is irregular and disturbed, laying near the bottom of the trough, is as absurd as to suppose it con­ tinued from Keppel's column to Elsecar, where it once stood at the former place 300 yards above the present Park Gate coal, and should therefore be 300 yards higher at Elsecar than as at present existing. In fine, the whole phenomena of this system of disturbances had been so ably described by Mr. Morton, who is perfectly acquainted with the country (with one slight exception, which he should mention, viz., that there is no general rise entirely to Leeds, as proved by the Silkstone and Bamsley levels; and that Billingley is not in the bottom of the trough, for the coal there rises S. end 5i inches per yard,) that he should say no more up{m the subject.