APPENDIX. 



373 



sea, and to rise again in Ireland, France, Sweden, and Germany, and 

 thus to be connected with all the granitic ranges of the old continent. 

 It is scarcely requisite to remark, that, in presenting a general view 

 of the arrangement of the different classes of rocks in this manner, the 

 partial wavings or irregularities of the strata, and the inequality of 

 surface, presented by hills and valleys, must be necessarily disre- 

 garded. 



The primary rocks of England and Wales are described in various 

 parts of Chaps. V. and VI. in the present volume. The transition 

 rocks, including mountain limestone, are described in Chapter VII. 

 The coal formations in England, within the middle district (coloured 

 green in the map), extend on the eastern side of Northumberland and 

 Durham, from Berwick-on-Tweed to the river Tees ; but from thence 

 to the river Air (near Leeds), only the lowest beds of the coal forma- 

 tion occur, which contain but little workable coal. The Yorkshire 

 and Derl^yshire coal-field commences a little north of Leeds, and ex- 

 tends in breadth east and west about twenty-five miles, from Halifax 

 to Abberford, and in length about seventy miles, from Leeds to near 

 Nottingham and Derby. The breadth decreases southward, being lit- 

 tle more than twelve miles in Derbyshire. 



South-west of Derbyshire, there are a few small coal-fields near 

 Ashby-de-la-Zouch, and near Tamworth, Atherstone, and Coventry. 

 The latter coal-field, is the most southern situation in which mineral 

 coal has been discovered in the midland counties. 



On the north-west side of England, there is a small coal-field bor- 

 dering the sea in Cumberland, which extends from Whitehaven to 

 the north of Maryport. This coal-field, though small in extent, con- 

 tains seven beds of excellent workable coal. From its contiguity to 

 the sea, and its remoteness from other coal-fields, it may be consid- 

 ered, in proportion to its extent, as one of the most valuable coal 

 districts in England. In one mine, the coal is worked at the depth of 

 298 yards. The workings of some mines have been extended under 

 the sea. The next considerable coal-field is that of Lancashire : it is 

 separated from the Yorkshire coal-field by a range of lofty hills, on 

 the borders of the two counties, extending, on the west side of Colne, 

 to Blackstone Edge, and from thence to Axe Edge, on the border of 

 Derbyshire. These hills are principally composed of millstone grit 

 and shale, but are not covered by coal strata. On the western side 

 of these hills, the coal strata of the Lancashire coal-field commence, 

 dipping westward ; but they are broken and deranged by numerous 

 faults. The principal beds of coal are, — one of six feet in thickness, 

 and a lower one called the three-quarter bed. In some parts the 

 sandstone strata are of a deep red colour. The breadth of this coal- 

 field, from Macclesfield to Oldham, does not exceed five or six miles ; 

 but from Oldham it extends westward to Prescot, near Liverpool, and 

 from Prescot it extends in a north-east direction to Colne. 



Not far from the southern extremity of the Lancashire coal-field, 

 there is a small but valuable coal district, which supplies the potteries 

 near Newcastle in Staffordshire : this may properly be considered as 

 an extension of the Lancashire coal-field. The next important coal- 

 field is that of Dudley and Wolverhampton : it is about twenty miles 



