33O Mountains, Plains, and Escarpments. 



4 



landslips came in aid, and are still in 

 progress. This general description, with 

 local variations dependent on lithological 

 variations, and the dips, strikes, and 

 faults of the strata, may serve for much 

 of the Carboniferous ground in the middle 

 of the anticlinal curve, as far as the 

 northern borders of the Yorkshire and 

 Lancashire coal-fields. 



If we now construct a section from 

 the Menai Straits, across Snowdon and 

 over the Derbyshire hills to the east of 

 England, the arrangement of the strata 

 may be typified in the following manner 

 (fig. 67, and Map, line 17). In the west, 

 rise the older disturbed Silurian strata, 

 Nos. 1 to 3, which form the mountain 

 region of Wales. On the east of these 

 lies an upper portion of the Palaeozoic 

 rocks, 4, consisting of Carboniferous beds 

 with an escarpment facing west. They 

 are less disturbed than the underlying 

 Silurian strata on which they lie uncon- 

 formably. Then, in Cheshire, to the east 

 of the Dee, lie the great undulating 

 plains of the New Eed series, 6, and these 

 form plains because they consist of strata 

 that have never been much disturbed and 

 still lie nearly flat, and are soft and easily 

 denuded, whence, in part, the soft rolling 

 undulations of the scenery. Then more 

 easterly, from under the strata of New 

 Eed Sandstone, the disturbed Coal- 

 measures again rise, together with the 



