Coalfield

“ The northern coalfields are the L. Carboniferous one at Ballycastle, the high outliers of Millstone Grit and Coal-Measures round Lough Allen, and the Dungannon and Coalisland field in county Tyrone. The last named is in part concealed by Triassic strata. The only important occurrences of coal in the south are in eastern Tipperary, near Killenaule, and in the Leinster coalfield (counties Kilkenny and Carlow and Queen’s County) , where there is a high synclinal field, including Lower and Middle Coal-Measures, and resembling in structure the Forest of Dean area in England. ”

“ The most valuable seam in the whole Coalfield in point of thickness and quality is that called the High Main, of the mines situated between Newcastle and Shields. It there averages above 6 feet from the roof to the floor, contains a large proportion of bitumen, and is sufficiently hard to bear carriage without breaking into very small fragments. ”

“ The neighbouring Cheadle Coalfield comprises the lower 2000 ft., with the Crabtree, Woodhead and Dilhorne coals; two other little coalfields comprise only the lowest strata. The South Staffordshire coalfield has 500—1000 ft. ”

“ As the demand for coal increases, other collieries will doubtless be started at fresh localities outside the limits of the coalfield, for there can be no question that the Thick coal extends far to the eastward, under and beyond the town of Birmingham itself. ”

“ The outcrop of this formation broadens eastward until it is covered by the Durham coalfield which occupies the centre of the county from Newcastle and South Shields to Barnard Castle. The Coal Measures are about 2000 ft. thick and contain upwards of 100 seams of coal, including many of great importance—the Brockwell coal, Low Main coal and High Main coal are some of the well-known seams. Fireclays of great value are obtained from beneath many of the coal seams. ”

“ The general effect of the three great north-north-east and south-south-west faults, the Brockmoor, the Corbyn's Hall and the Shut End, is to throw down the measures towards the west, and extend the coalfield in that direction. If it had not been for these breaks it seems likely that the outcrop of the Thick coal south of Brettell-lane might have run in a straight line north-north-east for that north of Turner's Hill by Cotwell End and Sedgley Hall farm. ”

“ From Macclesfield northward through Stockport is a narrow tongue of Lower and Middle Coal-Measures—an extension of the Lancashire coalfield. Coal is mined at Neston in the Wirral peninsula from beneath the Trias; it is a connecting link between the Lancashire and Flintshire coalfields. Glacial drift is thickly spread over all the lower ground; laminated red clays, stiff clay with northern erratics and lenticular sand masses with occasional gravels, are the common types. ”

“ The Coal Measures of the Warwickshire coalfield crop out in the north of the county between Nuneaton and Tamworth and contain valuable coal-seams; they pass conformably under the so-called Permian red sandstones and marls which are apparently the equivalents of the Keele Beds of Staffordshire, and like them should be grouped with the Coal Measures; they occupy a considerable area north and west of Coventry, and at Corley form high ground (625 ft.) ; in several places shafts have been sunk through them to the productive Coal Measures below. ”

“ Destination of the Minerals.—The greater part of the coal is consumed in the district for house purposes, for steam raising, for the manufacture of bricks, pottery, glass, salt, &c. The remainder is carried out of the [261] coalfield into the south and south-western districts of England by the London and North Western, Great Western, and Midland Railway Companies, for house and steam purposes. The gas coals and coke used in the Birmingham district are not the product of the South Staffordshire Coalmeasures, but are brought principally from North Staffordshire, Derbyshire, and Yorkshire. ”

“ The most important European coalfields are in Great Britain, Belgium and Germany. In Great Britain there is the South Welsh field, extending westward from the march of Monmouthshire to Kidwelly, and northward to Merthyr Tydfil. A midland group of coalfields extends from south Lancashire to the West Geographical distribution of coalfields. ”

“ The outcrop of a coal may be seen in the valley of the brook south of Castle Hill, while another outcrop may be seen in a little gulley on the north side of it in Beaudesert Old Park. Old coal-pits are scattered all over this old park, all of which were said to go down to the same coal, and none to have been more than about 30 yards deep. ”

“ The central portion of the coal-field.—The central portion of the coal-field lies in the hollow or basin between the Silurian ridge of the Dudley and Sedgley anticlinal and the Walsall elevation.
If we take Tipton old church, the Moat colliery, and Princes End and that neighbourhood as a centre, the beds, being there deepest, rise thence gently towards the surface in every direction except towards the south. ”

“ On the north side only, however, has it been followed under the basalt, and that for but a very slight distance; and in every instance in which this has been attempted the coal has been found to be "blacked" and to be fractured, and frequently to pass into "rock and rig." A coal is said in this district to be "blacked" when, by its near proximity to an igneous rock, it has become so altered as to lose all its brightness, and nearly, if not quite, all its inflammability. ”

“ To the north and to the east of the limestone hills lies the most noted of the Shropshire coalfields, that of Coalbrook Dale, which is rich also in iron, though its mineral wealth is becoming exhausted. ”

“ The minute partings of shale or earth between the different beds of coal in the Baremoor colliery sensibly thickened as they approached the swell and coalesced with it. In a practical point of view these swells are worthy of study, inasmuch as they often diminish or destroy the value of a tract of coal. They very frequently occur. I believe, in all coal-fields, but it is not always that they can be so well examined and understood as in the Thick coal of Staffordshire. ”

“ Blocks of granite and old trappean rocks, evidently belonging to the Great Northern drift, are found in great abundance all along the western boundary of the coal-field, especially about Bushbury, and thence towards Cannock. 'They occur abundantly also over all the New red sandstone country on the west of the coal-field. They may be found occasionally, but by no means abundantly, within the limits of the coal-field itself, but on its eastern side they are, as far as my recollection serves me, comparatively very rare. ”

“ Elliot remarks that, according to his estimates, ‘transport would neither be more costly nor more laborious than it has been in days gone by to convey coal the same distance after it was brought to the surface inland.’ The enormous importance of the subject is shown by the fact that ‘out of the minerals obtainable in Durham alone, one-third,’ Mr. Elliot tells us, ‘may be held to lie under the sea, and that all coalfields having a similar inclination of strata, and bordering on the ocean, will be similarly enlarged. ”

“ I think, see reason to conclude that the east and west boundaries of the coal-field are not only genuine faults, clean-cut fractures, but that they were produced late in the New red sandstone period, if not subsequently to it altogether. ”

“ When, however, the accumoulation of the vast quantity of vegetable matter necessary for the production of the Thick coal was nearly completed, a very partial and local subsidence took place in one or two localities, bending down the previously formed beds into a hollow or pool of water, sufficiently deep for 128 feet of shale and sandstone to be accumulated, and thus another level floor formed for the growth of the upper bed of coal, which grew partly on the shale and sandstone, and partly on the undepressed coal. ”

“ Rock faults, swells, rolls, &c.—There are some remarkable peculiarities and irregularities of structure, which, although by no means peculiar to the Thick coal, but occurring now and then in all beds of coal in all coal-fields, are yet so well seen in the Thick coal on account of the scale on which they are exhibited, that it is worth while to take this opportunity of describing them a little more in detail. ”

“ If these coals be other than the Thick coal they must be either above it or below it. If they are entirely above it then the Thick coal must lie in the district between Essington and Wyrley on the one side and Pelsall and the Brown Hills on the other, and must crop out to the surface in that district, inasmuch as beds, which are certainly below the Thick coal, themselves crop out to the eastward of it. ”

“ I have been told by a considerable proprietor of coal-mines in these counties, and I believe it is an opinion very generally entertained, that this sandstone always cuts off the coal-measures, and that it is useless to search for coal beyond or beneath it. ”

“ J. Kenyon Blackwell was kind enough to accompany me in tracing the crop of the Thick coal hereabouts, with his ground bailiff, Mr. Waterfield. The outcrop of the coal was perfectly well marked by the occurrence, at the surface of the ground of fragments of "shattery." This is the local name for a well-known indurated shale, streaked red and green, and baked almost into jasper. After extracting the coal, the fragments of coal and shale are piled up in the hollows to afford a partial support to the roof. ”

“ It occurs at the Baremoor colliery, about three miles south of Dudley. The Thick coal is worked all round the neighbourhood with its usual thickness and characters, and at a depth varying from 350 feet to 600 feet below the surface. A little above it is the usual Thick-coal rock, or sandstone, rather thicker, perhaps, than it is generally found in other parts of the coal-field. ”

“ The richest part of the field in amount of coal-beds, both absolutely and still more in proportion to the whole thickness of the measures in which they lie is between Wolverhampton and Bilston, where the lower coals are becoming rapidly thicker, and the Thick coal is still nearly unbroken and undiminished. ”

“ North of Highfield there is no mention at all of the Flying reed, it having either cropped out altogether, or been thrown out by the great Lanesfield fault.
Between Bilston and Wolverhampton, the "White coal" is always looked on as the top of the Thick coal. Here, however, we get still another change in the central part of the Thick coal, as a considerable mass of shale, sometimes containing ironstone, is interposed between the "Foot coal" and the "Slips coal." ”

“ This change, from a thickness of thirty feet of coal only, to one in which thirty feet of coal are distributed among 300 feet of shales and sandstones, can be shown to have taken place within a horizontal distance not exceeding five miles. It is a kind of change quite familiar to those who are accustomed to trace any set of beds continuously along their strike, though it is not often that it can be so clearly proved and followed out in detail as in the present instance. Two of the coals below the Thick coal also undergo a similar separation towards the north. ”

“ Wherever the bed known as the Upper Sulphur coal is mentioned in the pit sections, it is found to lie about 300 feet above the Thick coal, and about half that distance above the Two-foot or Little coal. The Upper Sulphur coal is mentioned in most of the pit sections in the latitude of Dudley, from Great Bridge to Kingswinford. ”

“ The Bottom coal, thus separated into two, was worked formerly for some distance along the outcrop north of Pelsall Heath, till it was dropped out of reach of the "old men" by downcast faults into that which may now be called the High Bridge trough. The corresponding upcast faults on the north side of this trough brought these coals again near the surface about the Brown Hills, and they were there gotten both by the "old men," and the men of the last and present generation. ”

“ The probable thickness of the upper and unproductive Coal-measures.— We have seen that in some part of the South Staffordshire coal-field there are 900 or 1,000 feet of Coal-measures above any of the workable beds of coal or ironstone. ”

“ The second opinion, and perhaps the most generally entertained now, is, that the plants entering into the composition of the coal were not drifted, but grew and perished on the very spot we now find them forming coal, just as our own peat bogs at the present day would form coal if buried for a vast series of years under a great accumulation of earthy matters. ”

“ We have already, in examining the base of the Coal-measures, seen the way in which at particular spots the lower beds of that formation filled up hollows in the Silurian rocks and obliterated their little pre-existing cliffs, and thus formed a smooth floor for the deposition of the chief mass of the Coal— measure beds. ”

“ The sandstones and coarser grained rocks are most capricious in their occurrence, and vary most suddenly in thickness and character.
Beds of coal are not only constant in thickness over very considerable areas, but also generally in quality and character. This is so much the case, that colliers and other persons who have been long engaged in handling the coals of a district will recognize detached blocks of different coals lying loose on the pit bank, even when taken to a distance of some miles from their own pits. ”