Coal field

“ In the great coal-field of South Wales, to which we must look for our main supply of anthracite, we are able to trace the action of heat in producing a whole series of different classes of coal in a single seam, which at one part is highly bituminous—soft, flaming coal, like the Wallsend, then it becomes harder and less bituminous, then semi-bituminous “steam coal,” then less and less flaming, until at last we have the hard, shiny form of purely carbonaceous coal, that may be handled without soiling the fingers, and which burns without flame, like coke or charcoal. ”

“ The rest of the outer circle of high land, on whose summit the observer has been supposed to be standing, and which so definitely marks the Forest coal-field, comprises the lower coal measures, containing the lower and upper Trenchard veins, the Coleford High Delf, with the Whittington and Nag’s Head seams, which together give about eleven feet of coal. ”

“ Mining began on the Tyne and continued on the Wear, where the industry has been largely developed. There are in all about 57 different seams in the Great Northern coal-field, varying in thickness from 1 inch to 5 feet 5 inches and 6 feet, and these seams comprise an aggregate of nearly 76 feet of coal. Taking the area of this field to be 750 square miles—a most probable estimate—we may classify the contents as household coal, steam coal, or those employed in steam-engine boilers, and coking coal, employed for making coke and gas. ”

“ These facts prepare us for the statement, of the truth of which good proof can now be given, that the change in the grouping of the beds was originally much more complete, even within the limits of the coal-field, and that the beds of coal which, coming together in the southern part of the field, form the Thick coal, are the very same beds, or some of them, which are worked now at Essington and Wyrley, and are there all more or less separated from each other by interposed shales and sandstones, so as to make a total thickness of over 300 feet. ”

“ All the conditions required for enhancing the value of a coal-field are here combined in such a remarkable manner as to make the extraction of a very superior coal easier and cheaper than in any other known instance.... ”

“ Wherever a coal-field now exists, there must formerly have been free access for a great river, or for a shallow sea, bearing sediment in the shape of sand and mud. When the coal-forest area became slowly depressed, the waters must have spread over it, and have deposited their burden upon the surface of the bed of coal, in the form of layers, which are now converted into shale, or sandstone. ”

“ The section of such a coal-field will show us coal and sandstone, or shale, alternating again and again—a yard or two of coal and hundreds of feet of shale or sandstone—until we come to the present surface every one of those deeply-buried coal-beds having been at one time a forest, growing under the full power of a brilliant sun, the result of solar forces, produced then, as now, by chemical phenomena taking place in the sun itself. Every cubic yard of coal in every coal-bed is the result of a very slow, but constant, change of a mass of vegetable matter ”

“ We have already considered the various kinds of plants and trees which have been discovered as contributing their remains to the formation of coal, and have now to attempt an explanation of how it came to be formed in so regular a manner over so wide an area.
Each of the British coal-fields is fairly extensive. The Yorkshire and Derbyshire coal-fields, together with the Lancashire coal-field, with which they were at one time in geological connection, give us an area of nearly 1000 square miles, and other British coal-fields show at least some hundreds of square miles. ”

“ Along their south-east margin, old coal-pits are abundant, and wherever a little valley cuts into them, the old coal-pits run down it for a short distance. Old coal-pits, with abundance of coal shale on their banks, are found on both sides of the Hednesford Hills, and everything goes to make it probable that at this northern side of the coal-field the boundary is formed by an unconformable overlap of the New red sandstone resting horizontally, or nearly so, on the slightly inclined edges of the Coal-measures. ”

“ They occupy the central area of the Mid-Lothian coal-field, and from their gentle inclination as compared with the lower strata that rise up from under them on either side of the basin, are known as the Flat Coals. Their - 233 - total thickness—that is to say, all that has escaped denudation—amounts to a thousand feet or more. They consist chiefly of sandstones, shales, ironstones, and fire-clays, with from twenty to twenty-five seams of coal, of which sixteen are thick enough to be worked. Their similarity to the Edge coals below points to a similarity in the conditions of formation. ”

“ 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 carboniferous measures are the highest and latest geological formation in the great coal fields of the United States. Therefore where the strata have not been disturbed by flexure the coal seams lie near the surface. This is generally the case in the bituminous districts, and it is also partially true in the northern anthracite coal field. Deep mining is necessary only in the middle and southern anthracite coal fields, where the folds are close and precipitous, and the deep and narrow basins formed by them have been filled with deposits of a later geologic age. ”

“ 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. ”

“ As the coal forests began to flourish, the productus seems to have waned; but it is still sometimes found in considerable numbers in the ironstones and limestones intercalated among the coal seams of northern England and central Scotland. In the period which succeeded the coal, that, namely, of the Permian, it seems to have died out altogether, at least no trace of its remains have as yet been detected in strata of a later age. But whilst it lived, the productus must have enjoyed a wide range - 100 - of climate, for its valves have been found by thousands both in the old world and in the new. ”

“ The best quality amongst Indian coals has come from a small coal-field of about 11 square miles in extent, situated at Kurhurbali on the East Indian Railway. Other coal-fields are found at Jherria and on the Sone River, in Bengal, and at Mopani on the Nerbudda. Much is expected in future from the large coal-field of the Wardha and Chanda districts, in the Central Provinces, the coal of which may eventually prove to be of Permian age. ”

“ Hence, until we know more of the conditions under which vegetation may accumulate at river-mouths in such a climate as the coal plants are conjectured to have enjoyed, calculations of the amount of time required for the formation of a great series of coal-bearing strata must be regarded as premature. In the present instance, we can but affirm that the growth of the four-foot coal-seam probably occupied many long years, even at the most rapid rate of accumulation known to us. ”

“ Two-thirds of the coal mined in the United States is obtained from the Appalachian field, extending from New York to Alabama, Pennsylvania being the largest coal-producing state in the Union. In the iron and steel industries [Pg 23] most of the coal is coked, as it is better for blast-furnace use in this form, giving greater heat and containing less sulphur or other injurious substances than coal. ”

“ Some of our coal crops out at the surface in places where through the ages wind and weather have worn away the overlying clay, stone, and slate. This can be gathered like wood in the forest without danger. The amount of such coal is commercially unimportant. Some lies only a few feet underground so that it is possible to take it by stripping away the thin overlying material and blast and scoop it out with a steam shovel. There are [Pg 44] some stripping mines in the anthracite field and a considerable number in the alluvial plains of the West. ”

“ But with the revival of business, mining was again begun in the Richmond field, and from 1874 to the present time the industry has prospered and grown, and Virginia has furnished to the country at large a considerable amount of an excellent quality of bituminous [40] coal. This coal bed covers an area of about 180 square miles, and has an average thickness of twenty-four feet. It is supposed to contain about 50,000,000 of tons yet unmined.
Another of the early discoveries of coal in the United States was that of the Rhode Island anthracite bed in 1760. ”

“ 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. ”

“ Such vertical stems are familiar to our coal-miners, under the name of coal-pipes. They are much dreaded, for almost every year in the Bristol, Newcastle, and other coal-fields, they are the cause of fatal accidents. Each cylindrical cast of a tree, formed of solid sandstone, and increasing gradually in size towards the base, and being without branches, has its whole weight thrown downward, and receives no support from the coating of friable coal which has replaced the bark. ”

“ The articles published on this subject do not allow any doubt that coal fields are there, and coal is now, you know, the basis of all our commercial industry. Without mentioning the coal which is used every year in firing and heating, we might think of coal used for many other purposes, of which I could mention a hundred different ones. It is certain that coal is the most precious substance, and will some day, on account of the large consumption of it; fail in its supply. Before 500 years have passed the coal mines which are at present in use will have stopped giving coal. ”

“ For more than two years the Government has been conducting a series of experiments in a very thorough manner, endeavoring to ascertain the gas values of the great lignite coal fields between Boulder and Denver. It has been discovered that the converting of the coal into gas gives it double the efficiency for use as a motor power for engine or for fuel than can be gained from the coal in its natural state. ”

“ Aside from the coal-measures below the sandstone, there have been found above the sandstone, north of Pine Mountain, 1650 feet of coal-measures, containing nine beds of coal of workable thickness, and between Pine and Cumberland mountains there is a greater thickness of coal-measures, containing twelve or more workable beds. Some of these are coking coals of great excellence. Cannel-coals are found in sixteen of the counties in the eastern coal-fields. Two of them at least are of unexampled richness and purity. The value of a cannel-coal is determined by its volatile combustible matter. ”

“ The general characteristics of these coal-fields have been the subject of much investigation, and some very interesting and valuable results have been reached. These will appear in the final reports. The quantity of available coal is practically inexhaustible, and the mines that can be economically worked are of great number. ”

“ It is only where there is a dearth of handy fuel, ready to be had, perhaps, by the simple felling of a few trees, that man commences to dig into the earth for his fuel. But although on the continent not yet occupying so prominent a position in public estimation as do coal-fields in Great Britain, those of the former have one conspicuous characteristic, viz., the great thickness of some of the individual seams. ”

“ In these days, in the anthracite coal fields, there is hardly an area of any great extent in which mines have not been actually opened. These mines, therefore, in [78] the facilities they afford for studying exposed strata and developed coal seams, offer the best means of acquiring knowledge concerning the coal beds of adjoining tracts. In a country where no surface indications of coal are found over a large area, it is hardly worth while to explore for it by boring. ”

“ On the west of the chain of mountains the foldings become gentler, and the coal assumes an almost horizontal position. In passing through Ohio we find a saddle-back ridge or anticline of more ancient strata than the coal, and in consequence of this, we have a physical boundary placed upon the coal-fields on each side. ”

“ 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. ”