The Peak District is an upland area in England at the southern end of the Pennines. Mostly in northern Derbyshire, it includes parts of Cheshire, Greater Manchester, Staffordshire, West Yorkshire and South Yorkshire. It can be split into the Dark Peak, where most moorland is found and the geology gritstone, and the White Peak, a limestone area of valleys and gorges cutting through the limestone plateau. The Dark Peak forms an arc on the north, east and west sides; the White Peak covers the central and southern tracts. The historic Peak District is larger than the area of the National Park, which excludes major towns, quarries and industrial areas. It became the first of the national parks of England and Wales in 1951. Nearby Manchester, Stoke-on-Trent, Derby and Sheffield send millions of visitors a year. Some 20 million people live within an hour's journey. Inhabited from the Mesolithic era, it shows evidence from the Neolithic, Bronze and Iron Ages. Settled by the Romans and Anglo-Saxons, it remained largely agricultural; mining arose in the Middle Ages. Richard Arkwright built cotton mills early in the Industrial Revolution. As mining declined, quarrying grew.