 One of the best exposures of the Coal Measures is on the north east coast between Whitley Bay and Seaton Sluice.Around 280 million years ago, at the close of the Carboniferous period, the Variscan orogeny (mountain building period) caused major deformation in south west England.The general region of Variscan folding was south of an east–west line roughly from Avon to Kent, though lesser folding took place as far north as Derbyshire and Berwick-upon-Tweed.