Page:The American Cyclopædia (1879) Volume VI.djvu/612

600 ENGLAND of coal in the midland counties. On the N. TV. is the Cumberland and "Whitehaven coal field, extending along the coast to the north of Maryport ; some of its mines have been worked beyond low-water mark, and the convenience of shipping gives a high importance to their products. The Lancashire coal field lies W. of a range of hills that extends along the borders of this county and Yorkshire, separa- ting the two coal fields by the underlying shales and millstone grit of which they are composed. The strata of the coal formation on the W. side dip toward the west, and the margin of the field in this direction reaches to Prescot, near Liverpool, and extends N. E. toward Colne. A little beyond the southern extremity of the Lancashire coal field is that which sup- plies the potteries near Newcastle in Stafford- shire, and which, with those referred to as lying S. "W. of Derbyshire, makes up the central coal district as grouped by Conybeare and Phillips. These include the fields of Ashby de la Zouch and "Warwickshire. In the South Stafford or Dudley coal field the coal has been worked in a single bed 30 ft. thick, and at one locality it has reached a thickness of more than 45 ft. The western coal district comprises the mines in North Wales, the island of Anglesea, and Flintshire. The middle western or Shropshire district comprises those of the Glee hills, Cole- brook dale, Shrewsbury, &c. ; the south- western district, those of the Forest of Dean, South Gloucester, and Somerset, on both sides of the river Avon, and the coal field of the S. coast of Wales, bordering the British chan- nel for 100 m. E. and W.; and stretching in- land toward the north from 5 to 20 m. This field is in convenient proximity to the copper mines of Cprnwall, the ores from which are transported to the great smelting establish- ments on tide water near the coal mines. Much of the coal of this region is semi-anthra- cite, like that of the Cumberland coal field of Maryland, and some is true anthracite. The latter was first successfully applied upon a large scale to the smelting of iron ores in this dis- trict at the Crane iron works. Iron ores abound in the coal measures of this field as well as in many of the others, especially that of Dudley and Wolverhampton, near Birmingham. The same measures also yield fire clay and lime- stone, and the millstone grit which underlies and holds as in a cup the coal measures furnishes a most durable building stone. Besides the coal measures scattered over the area in which coal and iron are found, and the newer forma- tions which here and there overlie them, there are frequent patches, like islands, of rocks of older date, which have intruded through the carboniferous strata and the later formations above them. These are of granite, syenite, and metamorphic slates. Some are basaltic dikes, and one such of extraordinary extent appears from under the alluvium on the coast of the North sea, near Harwood dale, and is thence traced toward the N. W. across the Tees to the western part of Durham. It traverses strata of the lias, oolite, the coal measures, and of the metalliferous or mountain limestone of the lower carboniferous group. Its length is from 50 to 60 m., and in some places it is seen only 25 to 30 ft. thick, dipping at a steep angle. The mountain limestone is productive in lead, cop- per, and zinc ores in three districts of Eng- land. Veins of galena near Alston moor in Cumberland traverse adjoining beds of lime- stone and sandstone, yielding well in the for- mer and poorly in the latter. Others are found in the same county, as also in Durham and Yorkshire, in the upper portions of the valleys of the Tyne, the Wear, and the Tees. Pyritous copper is obtained S. W. of Alston moor, and near Ulverstone beds of red hematite alternate with those of the same limestone. A second district is in Derbyshire and the contiguous parts of the neighboring counties. Zinc blende is economically worked in this district, which also includes the copper mine of Ecton in Staffordshire. The third district is in the N. E. part of Wales, where mines of galena andcala- mine have long been profitably worked, lying partly in the mountain limestone and partly in older formations. Bordering the coal fields frequently are seen the strata of the old red sandstone and other rocks of the Devonian series; and from beneath these appear the older and lower fossiliferous strata of the Si- lurian and Cambrian formations ; they produce little of economical importance. The metallif- erous districts of Cornwall and Devonshire are noticed in the articles upon those counties. The granitic rocks and metamorphic slates, such as are seen in this portion of England, are repeated in North Wales, where the argil- laceous slates are worked in the immense quar- ries near Bangor. The same rocks occur again in the N. W. part of Yorkshire and Lancashire, and are traced through Westmoreland and Cumberland into Scotland. The granite, often disintegrating rapidly, produces the white clay called kaolin, which is used in making fine porcelain; but it affords little good building stone, and there are no important quarries of this rock in England. Good building stone is not readily found in any of the formations ; and the want of durable materials is the more sen- sibly felt because the humid atmosphere pro- duces a rapid disintegration of stone exposed to it. England is deficient in fine marbles and in good iron ores. The best of the latter are the hematites ; but those chiefly employed in the immense production of iron are the poor argillaceous ores of the coal formation. For making the excellent cast steel for which Eng- lish manufacturers are celebrated, the better iron from the magnetic and specular ores of Norway and Sweden is largely imported. The annual produce of salt is over 1,000,000 tons, a large part of which is exported to America. The climate is subject to considerable varia- tions of heat and cold, and of dryness and moisture, but the winters are not severe for