10 THE BRITISH ISLES. 



affording excellent pasture to sheep, and agriculture is successfully carried on 

 in the Tweeddale and other valleys. 



A gap, through which passes the railway from Newcastle to Carlisle, and 

 which lies at an elevation of only 446 feet above the level of the sea, separates the 

 Cheviot Hills from a broad range of carboniferous rocks which forms the back- 

 bone of Northern England, and stretches from Northumberland to Derbyshire. 

 This is the Pennine chain, a region of moors, heaths, and grassy uplands, inter- 

 sected by verdant valleys abounding in picturesque scenery. In the west this 

 chain presents a steep slope towards the Irish Sea, whilst to the east it dips down 

 gently, and finally disappears beneath a band of magnesian limestone, which 

 separates the carboniferous rocks from the more recent formations occupying the 

 plain of York. The wealth of the Pennine chain in coal and iron has attracted 

 to it a dense population, and flourishing manufacturing towns have arisen upon 

 what were once desolate moorlands. 



A transverse ridge, crossed by the pass of Shap Fell, which joins the narrow 

 glen of the Lune to the broad and fertile plain of the Eden, and through which 

 runs one of the two main roads connecting England and Scotland, joins the 

 Pennine range to the mountain group of Cumbria. Consisting largely of Silurian 



Fig. 5. — Section from Snowdon to the East of England. 

 Accordmg' to Professor Ramsay. 



Pennine Ra. Lincoln 



.^*'^5!,.. OU..I,:.» Di,i c. , MagnesiEimest Oolite Wolds. 



Silttriaa Jocks _ .^^ Cheshire Plain. Q^bomf? Rocks 



New Red Sandstone. ^_ 



Yorl< Plain. 



Lias 



slates, this mountain group is famous for its pastoral scenery, its lakes and wooded 

 valleys. 



The broad plain of Chester separates the Pennine chain from the Cambrian 

 or Welsh mountains, composed of highly disturbed and distorted strata of Silurian 

 and Cambrian slates, intermingled with igneous rocks, and interbedded with lavas 

 and beds of volcanic ashes. In the south-east these ancient rocks are overlaid 

 successively by old red sandstone and carboniferous limestone, and there the 

 country, though hilly and even mountainous, is naturally fertile. In the remainder 

 of "Wales, however, although there are not wanting broad alluvial valleys 

 bounded by wooded hills, vast tracts are covered with heath, and are only fit for 

 pasture. 



When we cross the Bristol Channel we enter the last mountainous region of 

 England — that which comprehends the counties of Devon and Cornwall, and 

 attains its highest elevation in the granitic moorlands of Dartmoor. Geolo- 

 gically this region differs totally from Wales, Silurian rocks being altogether 

 absent, and Devonian strata the oldest formation met with. This south-western 

 peninsula of England is, in fact, closely allied to the peninsula of Brittany in 

 France, from which it is severed now by the Channel, but whence it derived its 

 population, and also, in part at least, its flora. Its mountain ranges and hills are 



