The South Downs National Park is England's newest National Park, having become fully operational on 1 April 2011. The park, covering an area of in southern England, stretches for from Winchester in the west to Eastbourne in the east through the counties of Hampshire, West Sussex and East Sussex. The national park covers the chalk hills of the South Downs (which on the English Channel coast form the white cliffs of the Seven Sisters and Beachy Head) and a substantial part of a separate physiographic region, the western Weald, with its heavily wooded sandstone and clay hills and vales. The South Downs Way spans the entire length of the park and is the only National Trail that lies wholly within a national park.