Page:Encyclopædia Britannica, Ninth Edition, v. 18.djvu/527

PENNSYLVANIA 501 Three anthracite coal-regions in eastern Pennsylvania are recog nized by railroad men, coal-dealers, and statisticians ; but they do not exactly correspond to the three anthracite coal-fields of the geological survey reports. (1) By the Schuylkill region is meant all the surface of coal-land which is drained by that river, with two small additions from the upper water-basins of the Shamo- kiu and Swatara rivers, affluents of the Susquehanna. In 1822 it supplied the Philadelphia market with 1480 tons of coal ; in 1880 it distributed, in all directions along the lines of the Reading Rail road, 9,500,000 tons. (2) By the Lehigh region is meant all the coal-lands on that river, furnishing in 1821 1073 tons, and in 1882 5,700,000, chiefly to the city of New York. (3) By the Wyoming region is meant the isolated valley of the Susquehanna (north branch) and Lackawanna rivers, commencing its shipments in 1829 with 7000, and sending in 1882 14,000,000 tons of coal eastward, north ward, and westward, to Boston, Montreal, and Chicago. In 1883 these three regions shipped a total of 31,800,000 tons. The three anthracite coal-fields into which the region divides itself geologically the southern, the middle, and the northern are three groups of narrow parallel basins filled with crumpled Coal- measures. Each field has a characteristic grouping of its basins different from the other two : the southern in perfectly straight lines, except at its western end, which has a long fork or fish-tail ; the middle in echelon ; the northern in a long sweeping curve from west by east to north. The southern field has for its southern border a sharp low mountain-ridge, 62 miles long, bearing about N. by 60^ E., and ending abruptly westward near the Susquehanna river and eastward at the Lehigh river. It is gapped in four places, by the Swatara, by the Schuylkill, and by its two principal branches, giving passage to three railways and two canals, one of which has been abandoned and the other is little ised. In this mountain the lower Coal-measures descend vertically to a depth of 3000 feet below tide-level, and then rise again in a series of waves to the top of a much higher mountain which borders the field upon the north. From the top of this broad mountain the Coal-measures have been swept away. They are next seen descending steeply northward into the middle iield, where they sink to various depths of 1000 or 2000 feet below sea-level, rolling six times so as to make that number of mining basins, and then rise into the air, along a bounding mountain at the northern edge of the field, not to de scend again to the present surface of the earth for 40 miles. Only the lowest beds, however, appear there in narrow strips upon the highest plateau of the State, and not as anthracite, but as bitu minous coal. This description, however, only applies to the western division of the middle field. Its eastern division has a very different character. On the broad rolling top of the Beaver Meadow Moun tains, west of the Lehigh river, lie a group of closely-folded parallel troughs, in which the coal-beds descend steeply to depths of 1000 or 2000 feet, and rapidly rise again to the surface, each trough being pointed at both ends and disappearing on the summits of mountain-spurs, which look down upon deeply-indented red-shale valleys. The collieries of this eastern division of the middle field are all on very high land, from 1600 to 1800 feet above the sea; and branch railroads descend from them by steep gradients to the two rival main lines, which follow the banks of the Lehigh and Dela ware rivers to the Atlantic coast. The northern field corresponds exactly to the Wyoming region. It is a moon-shaped trough, 50 miles long by 6 miles wide, tapering to a point both ways. Its eastern half is drained by the Lacka wanna river westward into the Susquehanna river, where the latter breaks through the northern mountain-wall and begins to meander westward through the Kingston iiats in the centre of the coal-field made famous by the incidents of Indian warfare. A few miles farther on the river breaks half through the northern wall, split ting it lengthwise, and then cuts olf the western point of the basin, leaving a little patch of it capping the isolated spur. This magni ficent coal-field is traversed diagonally by anticlinal and synclinal folds in the Coal-measures in such a manner as to subdivide it into more than thirty small coal-basins, all connected underground, the deepest of which hold more than 3000 feet of Coal-measures ; so that in a hilltop near Wilkesbarre fossil-shells of the Permian formation, the uppermost division of the Carboniferous system, have been collected. Until the maps of the anthracite section of the State Geological Survey have been completed, the area of anthracite coal-land in all three fields cannot be accurately stated. The total number of coal-beds cannot be stated, because some are hardly noticeable ; others are composed of several layers separated elsewhere by 50 or 100 feet of intervening rock. The identification of the beds across the intervals which separate the fields, and even from colliery to colliery, is not in all cases satisfactory. It may, however, be said generally that the whole column of Coal-measures contains more than a hundred coal-beds. Less than one -fourth of these have hitherto been considered of desirable size and quality for mining. Most of the output in past years and at present comes from five or six of them, from the Lykens valley bed, from the Buck Mountain bed, especially from the Mammoth bed all of 1 them white ash and from two or three red ash beds next higher in the series. The first quantities of coal which were sent to the market came from an open quarry on the summit of the mountain at Mauch Chunk, where the Mammoth bed is 60 feet thick. In subsequent years a long range of extensive collieries were created on the Mine Hill slope of the bed behind Pottsville. Later still the Mahanoy and Shenandoah collieries were established behind the Broad Mountain. From early years the great bed was worked in the "Wyoming region by the Baltimore Company. Other cor porations have extensively exploited it throughout the valley. Old mines in this bed are worked on a great scale also at Hazelton and Beaver Meadow, and later plants were made at Jeanesville, Clifton, and elsewhere. A choice though smaller bed, called the Buck Mountain vein, extends through all three fields, and is largely mined in many places, sometimes in tunnel-connexion with the Mammoth and sometimes alone. The Lykens valley bed, holding 10 and 12 feet of exceedingly choice coal, lies near the bottom of the Millstone grit (the base of the Coal-measures), but is scarcely workable anywhere except at the western end of the southern field. The waste in mining anthracite coal is enormous, although it has been somewhat diminished by the concentration of most of the coal-properties under the control of a few railway companies, who employ competent engineers and superintendents. But the markets demand the delivery of the coal in sizes. Iron furnaces alone accept the run of the mine. The <; breaker, " an anthracite inven tion, and a monster of destruction, is an edifice of wood and iron 100 feet high, furnished with slopes and lifts to take the mine- cars to the top, with rollers set with teeth to crush the larger lumps, with bolting screens to separate the sizes, with picking banks and boys to throw out slate descending the shoots, and with bays or pockets from which the coal is drawn at will to fill railway trains passing underneath. The waste is carted off to a neighbour ing hillside. Hills of this "dust," 100 feet high and hundreds of feet long, encumber the country, and awaken the anxiety of proprietors respecting its future disposal. All plans for utilizing it cheaply on a large scale have as yet failed, and no serious change in the situation can take place until the supply in the earth begins to fail. The time for that is distant. The annual output can reach 50,000,000 tons, and, in spite of the waste, can continue at that figure for three centuries. An exact calculation of solid con tents in the ground, of waste in mining and breaking, and of quantity sent to market has been made for only one division of one iield. At the eastern end of the southern field, for instance, six beds, as yet locally worked by only thirteen collieries (four of them now abandoned), contained originally 1,033,000,000 tons, of which only 54,000,000 have been extracted (between 1820 and 1882), leaving 979,000,000 tons still untouched. The output in 1820 was less than 400 tons, that of 1849 nearly 400,000 tons, that of 1882 838,000. In a few years it will reach 2,000,000, and might con tinue at that rate five centuries. The number of working collieries in the anthracite region is con stantly changing. The list for 1881-82, reported by the official mine inspectors, numbers 141 in the northern field, 51 in the eastern middle, 91 in the western middle, and 70 in the southern field, 353 collieries in all. The fuel they send to market is both white coal from the lower and red-ash coal from the higher beds of the series, the market sizes being designated egg, stove, chestnut, pea, and buckwheat. By sampling carefully the contents of five cars from one colliery carrying each a different size of coal, and analysing the samples, it was found that, while there was little difference in the percentage of water (say 1 7), of sulphur (say 7), and of volatile matter (say 4 0), the percentage of ash regularly increased as the size diminished (egg 5 662, stove 10 174, chestnut 12 666, pea 14 664, buckwheat 16 620), showing the finer breakage of the slaty layers, and the mixture of slate-dust with the smaller sizes of coal. The percentage of solid carbon, of course, diminished directly with the size, from 88 5 in egg-coal to 76 9 in buckwheat. The coal- dust of the heaps about the mines, before alluded to, is therefore, no doubt, still lower in solid carbon ; yet Captain Wootten s dust- burning locomotives on the Reading Railroad have been a success ; and the dust or " braize of the Philadelphia coal-yards is sold for use in fire-boxes of suitable construction. The bituminous coal-region of Pennsylvania covers the western third of the State, the greatest thickness of Coal-measures being in the south-western corner. Six wide parallel basins sweep round from the boundary-line with New York State south-westward into Ohio and West Virginia. The summit of the Alleghany Mountain, containing the lowest coals, limits the region towards the south east ; an irregular line parallel with and 30 miles distant from the shore of Lake Erie limits it on the north-west. The basins all gradually deepen going south-west, and are all subdivided into smaller local basins by gentle rolls. In one or two neighbourhoods the coal-beds dip as much as 30" ; but over almost the entire area they are so nearly horizontal that a dip of 2 or 3 a is exceptionally great. Over thousands of square miles they lie as flat as geological formations can ever lie, considering the accidents of original deposi-