IOS THE STORY OF THE EARTH. 



the South of England and Wales, but mostly in 

 thin beds. 



The coal was more widely spread in former 

 geological ages than it is at the present time, 

 though there is no reason to suppose that the 

 vegetable growth ever extended continuously over 

 the country. The several coal-fields are basin- 

 shaped depressions, which have been isolated from 

 each other, sometimes by denudation. First there 

 has been the Compression which elevated the Pen- 

 nine chain and Wales. This divided the coal-fields 

 into longitudinal series, stretching south on each 

 side of the Pennine chain. Then the country was 

 compressed in the opposite direction, forming 

 folds which run from east to west. An upward 

 thrust divides the coal-field of Northumberland 

 and Durham from that of Yorkshire and Notting- 

 ham. Its effects are also seen in the separation 

 of the Cumberland field from the South Lancashire 

 coal-field. The folds which isolate the South 



Wales and Forest of Dean coal-fields and the 



Somerset coal-fields lie further south. Afterwards 

 denudation removed the summits of the anticlinal 

 folds, and the coal-fields remained in basin-shaped 

 depressions. 



Coal has been found by boring beneath newer 



rocks at Burford in Oxfordshire; and at Dover; 



so that these east to west folds of the primary 



strata beneath the newer rocks, probably extend 



continuous with the coal of Belgium. 



( 'oal Plants. 



About half-a-dozen terrestrial plants which are 

 imperfectly known, have been described from 



jo* k^ older t han th< Devoi an. The flora of the 



