The most northerly county of England, lies on the border of Scotland, from which it is separated by the Cheviots and the Tweed; its eastern shore, off which lie the Farne Islands, Lindisfarne, and Coquet Isle, N. of Durham, fronts the North Sea; is fifth in size of the English counties; in the N. the Cheviot slopes form excellent pasturage, but the Pennine Range towards the W. presents dreary and less valuable moorland; on the W. are arable lowlands; Tweed, Tyne, Till, Alne, Wansbeck, are the chief rivers. Its great coal-field in the S.E. is the most celebrated in the world, and is the county's greatest source of wealth, and includes upwards of 100 collieries; Newcastle, Alnwick (county town), Hexham, and North Shields are the principal towns. Within its borders were fought the battles of Otterburn, Homildon Hill, and Flodden.