MINERAL DISTRICTS OF ENGLAND. 



11 



level. This forest appears to have extended eastward, as stumps of 

 trees and roots may be seen at low-water at a considerable distance 

 from the coast. 



West of the line a a a there is an important change in the mineral 

 productions ; from thence to the line c c c the lower secondary stra- 

 ta appear, and most of the principal coal districts in England occur 

 between the lines a a a and c c c. It is remarkable, that few if 

 any regular metallic veins are foumd in this division. The lower 

 secondary strata are also continued west of the line c c c, through 

 the midland and northern countries, but rocks of the transition series 

 occasionally appear in this part of our island. A very extensive 

 coal district occurs in that part of South Wales bordering the Bristol 

 Channel. On the east of the line c c c it may be remarked, that 

 the strata generally incline or dip to the south-east ; west of this line 

 they are more irregular, and dip in various directions. 



West of the part composed of the lower secondary strata, and 

 coloured green, we meet with rocks of the primary and transition 

 classes, in which metallic ores are found ; they constitute the alpine 

 parts of England, passing through Cornwall and Devonshire, into 

 North Wales, and the north-west parts of Yorkshire and Lancashire, 

 and through Westmoreland and Cumberland, into Scodand. This 

 part is coloured red ; rocks of the primary class occur chiefly in the 

 parts distinguished by dark lines. 



Near the center of England, at Charnwood Forest in Leicester- 

 shire, and at the Malvern Hills in Worcestershire and Herefordshire, 

 the primary rocks pierce through the secondary strata, and compose 

 two small districts of primitive country, surrounded by secondary 

 strata. Also in the counties of Derbyshire and in the West Riding 

 of Yorkshire, and part of Cumberland and Westmoreland, rocks of 

 transition or mountain limestone rise to a considerable elevation from 

 beneath the secondary strata, which occur east and west of them ; 

 some of these limestone mountains are rich in metallic ores. Along 

 the line e e beds of rock-salt and the principal springs of brine are 

 situated. 



It must be kept in mind when observing this map, that the tertiary 

 strata lie upon the secondary, and the secondary upon the transition 

 and primary rocks. Now, if the teruary and secondary strata had 

 both extended to the western counties, it is obvious that we could 

 have had no knowledge of the existence of the lower series but by 

 boring or sinking through the upper series ; and the aggregate thick- 

 ness of these exceeds the power of the miner to pierce through. 

 The tertiary strata, however, only cover a part of the secondary, and 

 the secondary do not cover the whole of the lower series ; so that in 

 travelling westward, we come immediately upon the lower strata in 

 succession, as they rise from underneath each other ; for, as 1 before 

 observed, the general inclination or dip of the beds is towards the 

 south-east. The action of the sea upon our coasts and cliiFs, has ex= 



