In Yorkshire there are detached coal-fields, very limited in extent, being small insulated coal-basins, lying in hollows in the gritstone. They occur near Middleham, Leyburne, Thorpefell, near Burnsell, and as far west as Kettlewell. Southward of these is an exten sive coal-field, which occupies an area extend ing north and south from a little to the north east of Leeds nearly to Derby, a distance of more than 65 miles ; its greatest width, 23 miles, is on the north, reaching nearly as far as Halifax to the west. The strata of this coal-formation are very numerous; the coal seams are about 30 in number, varying from 6 inches to 11 feet in thickness. Since the opening of the Midland Railway, which tra verses this coal-field, the working of the col lieries has been vastly extended by the facili ties for inland carriage. In north Stafford shire there are two detached coal-fields : the one situated on the N. E. of Newcastle-under Lyme, distinguished as the Pottery Coal Field ; the other at Cheadle, to the east of the first. The first measures from 6 to 10 miles in every direction; the second, from 3 to 5 miles. Thirty-two beds of coal have been met with, from 3 to 10 feet thick, and at depths from 50 to 400 yards. The South Lancashire coal field forms an area somewhat in the shape of a crescent, having Manchester nearly in the centre ; and northward of this are the North Lancashire and the Whitehaven beds; in the latter, some of the seams are very thick and of the finest quality; the shafts are very deep, and some of the mines are worked under the sea.
The South Staffordshire coal-field is about 20 miles long by 7 broad. Many coal-seams, of eight, six, and four feet in thickness, are worked in the northern portion of this field; but the southern portion is of much more im• portance, as it contains seams from 30 to 45 feet in thickness. This enormous thickness is however not one continuous seam, but a number of seams, divided by layers of what the miners call band, which are very thin beds of clay-slate. The working of these thick seams is not so profitable as might be sup posed. The pillars left standing in order to support the high roof are estimated at about one-third of the whole coal in the bed, and the small coal left in the mine is about equal to another third, so that only one third of the whole is at present taken out of the mine. This district supplies coal to the numerous iron-works in the immediate neighbourhood, and the manufactories of Birmingham. and its vicinity; besides which, all the neighbouring counties, as far south as Reading and Glou cester, are supplied by means of inland navi gation. Leicestershire and Warwickshire have small coal fields, independent of the one here noticed.
In North Wales, a valley crosses the Isle of Anglosea, parallel to the Menai Straits, and is flanked on both sides by parallel bands of carboniferous limestone. Coal of good quality
exists here, and a few mines have been suc cessfully opened. In Flintshire a coal-field exists, extending north and south from the Dee to Oswestry, about 30 miles: not conti nuously however, but in patches. It is sup posed that the seams pass under the Dee, and join those of Lancashire. The Coalbrook Dale coal-field is composed of the usual alter nating strata, and comprises nearly 00 alterna tions ; the seams vary from a few inches to 5 eet in thickness ; they occur at depths from t00 to 700 feet.
The eoal-field of South Wales is upwards of 100 miles in length, and the average breadth in the counties of Monmouth, Glamorgan, Caermarthen, and part of Brecon, is from 18 to 20 miles ; it becomes much narrower in Pembrokeshire, being there only from 3 to 5 miles. This area extends from Pontypool on the cast, to St. Bride's Bay on the west, and forms a vast basin of limestone, in which all the strata of coal and ironstone are deposited. The lowest bed is 700 fathoms deep at the centre, and all the principal strata lie from 500 fathoms deep to this depth. But this district is intersected by deep valleys, which generally run in a north and south direction, intersecting the coal. By driving levels in the hills, the beds of coal are found without the labour and expense of sinking shafts ; there are also many pits in the low valleys. The seams vary from a few inches to 0 feet in thickness ; and their aggregate thickness is about 100 feet. On the south side of the basin, the coal is principally of a bituminous nature ; on the north-east it is a coking coal; on the north-west, stone coal. The occur rence of rich iron ore with or near the coal has led to the establishment of vast iron works in South Wales.
The Gloucester and Somerset coal-field is about 25 miles long by 11 wide. The seams of coal are very thin in comparison with those which are worked in the principal coal-fields of England, and in most of those would he rejected as not worth the working. The Forest of Dean contains a coal-field about 10 miles long by 6 wide.
The principal coal-district of Scotland occu pies the tract which forms the great central lowland of Scotland, and lies between the great transition chain on the south, and the still loftier primitive mountains of the High lands on the north. In the county of Had dington are three seams of good workable coal. There are a few mines in Fifeshire and Mid-Lothian. In Lanark the coal-fields are numerous and extensive. Throughout this district seven seams of coal are usually found within 415 feet of the surface ; five of these seams are of sufficient thickness to be wrought, and of good quality. Coal is found in various other parts of Scotland.