Page:Encyclopædia Britannica, Ninth Edition, v. 6.djvu/71

OEBMA.NX.J A L Oi conditions prevailing at the time of the older coal measures were repeated over a part of the same area in Cretaceous times. There are traces of thin discontinuous coal-beds in the Wealden strata of Sussex, but nowhere approaching to the extent of those in the Wealden strata of N. Germany. In the low ground north of Halle, small and irregular patches of coal measures are found at Wettin, Lobejun, and Plotz. These are probably the remains of a single coal-field which has been disturbed and broken up at the time of the eruption of a great mass of igneous rocks which is found in a nearly central position between them. The coal measures are also found in the Thiiringer Wald, the Schwarzwald, on the south side of the Harz, and in the Bavarian Oberpfalz, but none of these localities are im portant as centres of production. In Saxony there are two principal coal-fields, the first being that of the Plauens che Grand, near Dresden, which is chiefly interesting for the very disturbed condition of the measures, and the conse quent difficulty in working ; and the other that of Zwickau, which is one of the most important in Europe. It forms an elliptical basin, about 20 miles long, between Zwickau and Chemnitz, and from 6 to 7 miles in maximum breadth, the greater portion being covered by New Red Sandstone strata. The coal measures, which rest upon old argillaceous schists, are about 1700 feet thick at a maximum, containing 12 principal seams of coal, besides several smaller ones. The most important is the so-called soot coal (Russkohle), which at times attains to a thickness of 25 feet. The series is divided by Geinitz into groups, according to the prevailing character of the associated fossil plants, as follows : 1. Zone of Ferns, corresponding to the upper group. 2. Zone of Annularia and Calamites, or middle group. 3. Zone of Sigillaria, or lower group. A fourth, or Sagenaria zone, found in Silesia, corresponding to the culm measures of Devonshire, completes this classi fication. The most important coal-fields of Eastern Europe are those of Silesia. The Carboniferous limestone series and the lowest coal measures or culm strata reappear in these basins, and are associated with numerous valuable mineral deposits, mainly of zinc and lead ore. The coal-field of Lower Silesia and Bohemia forms a basin between Glatz, Waldenburg, Landshiit, and Schatzlar, about 38 miles long and 22 miles broad. The number of seams from 3^ to 5 feet thick is very considerable (from 35 to 50); but it is difficult to trace any one continuously for any great distance, as they are liable to change suddenly in character. The lower seams usually lie at a higher angle than those above them. There does not appear to be any relation between the coking power of the coals and their geological position, and the same seam often varies in quality in neighbouring mines. The upper Silesian coal district extends in several dis connected masses from Mahrisch-Ostrau in Moravia, in a N.W. direction, by Rybnik and Gleiwitz in Prussia, and Myslowitz in Poland, being held partly by Austria, Prussia, and Russia, the Prussian portion between Zrabze and Myslowitz being the most important, extending over 20 miles in length, by nearly 15 in breadth. The greatest thickness of coal in workable seams (from2|- to GO feet thick) is estimated at a total of 333 feet, the thickness of the measures beingabout 10,000 feet. A very large proportion of this coal-field is hidden by New Red and Cretaceous strata. The Tertiary coals or lignites of Germany are of consider able importance, being distributed over large areas, the seams often attaining a great thickness, although rarely continuous for any great distance. The principal deposits are situated in the lower parts of the valleys of the Rhine and the Elbe, in Nassau, and in the high ground of the Rhon in Bavaria. The lignite district of the Rhine ex tends from near Bonn down to Deutz and Bensberg below Cologne. The pigment known as Cologne earth is a sepia- coloured lignite, which can be ground to a fine powder when dried. In Nassau the so-called bituminous wood, a variety of lignite containing flattened masses of wood of a light brown colour, is very common. The produce of these districts is mainly consumed for house fuel and steam boilers, some small quantity having been used for the pro duction of paraffin and photogen oil. The coal-fields of the empire of Austria-Hungary are of Austria. very considerable interest, from the great diversity in their geological position. Coals of Carboniferous age are mainly confined to the northern provinces of Bohemia, Moravia, and Silesia ; but in Hungary and the Alpine- lands, especially in Styria, coals of Tertiary age are found, which approach very closely in composition and quality to those of the coal measures. First in importance among the former class, is the basin of Pilsen in Bohemia, which covers an area of about 300 square miles. It rests upon Silurian shale, and is covered unconformably by Permian conglomerate and sand stone. The coals vary considerably in different localities ; the total thickness of the workable seams, from 3 to 5 in number, does not exceed 20 feet. There is a remarkable bed of slaty cannel in the upper part of the series, which contains animal remains of Permian types associated with the ordinary coal flora. Another important basin, that of Schlan-Kladno, E. of Prague, appears along the north edge of the Silurian strata, extending for about 35 miles E. and W. At Kladno, where it is best developed, it contains two principal seams, of which the upper is from 10 to 20 feet, and the lower or main seam from 19 to 40 feet thick. At Rossitz, near Briinn, in Moravia, a belt of coal measure, resting upon crystalline rocks, has been consider ably worked. There are three seams, together from 27 to 30 feet thick. These beds are said to be the equivalent of the upper seams of Pilsen and Kladno. In Moravia, Silesia, and Poland the coal measures are associated with the mountain limestone, which in Central Germany, east of Westphalia, is generally absent. The upper Silesian coal-field is situated in Prussia, Austria, Sile sia, and Russian Poland, the largest portion being in the first country. The area of this basin is about 1700 square miles, a considerable portion of it being hidden by Secondary and Tertiary strata. In the Austrian portion at Ostrau in Moravia there are 370 seams, of which 117 are workable, with a thickness of about 350 feet of coal. The largest seams are situated in the upper series, the principal one being about 13 feet thick. The coals of the neighbour hood of Ostrau are very full of gas, which occasionally finds its way into the cellars of the houses in the tow r n, besides giving off large quantities of fire damp in the workings. A bore hole put down 150 feet to a seam of coal in 1852, gave off a stream of gas which was ignited at the surface, and has continued to burn, with a flame many feet in length, to the present time. The same coal-field extends into the district of Cracow, where it contains numerous seams of great thickness, which, however, have been but partially explored. In the Austrian Alps anthracitic coals occur at various points along the northern slopes, in strata of the age of the culm measures, but nowhere in any great quan tity. In the Carpathian countries true coal measures are not largely developed, the principal locality being near Reschitza in the Banat, where 4 seams, from 3 to 10 feet in thickness, are worked to a certain extent. At Steyerdorf, near Oravicza on the Danube, a remark able coal-field is found in the Lias. There arc 5 seams, from 3 to 7 feet in thickness, which are bent into an anticlinal, besides being disturbed by numerous faults. The coal is of a very good quality, yielding a coke suitable for

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