The South Downs are a range of chalk hills that extends for about 260 square miles (670 km2) across the south-eastern coastal counties of England from the Itchen Valley of Hampshire in the west to Beachy Head, in the Eastbourne Downland Estate, East Sussex, in the east. The Downs are bounded on the northern side by a steep escarpment, from whose crest there are extensive views northwards across the Weald. The South Downs National Park forms a much larger area than the chalk range of the South Downs and includes large parts of the Weald.
The South Downs are characterised by rolling chalk downland with close-cropped turf and dry valleys, and are recognised as one of the most important chalk landscapes in England. The range is one of the four main areas of chalkdownland in southern England.
The South Downs are relatively less populated compared to South East England as a whole, although there has been large-scale urban encroachment onto the chalk downland by major seaside resorts, including most notably Brighton and Hove. The South Downs have been inhabited since ancient times and at periods the area has supported a large population, particularly during Romano-British times. There is a rich heritage of historical features and archaeological remains, including defensive sites, burial mounds and field boundaries. Within the South Downs Environmentally Sensitive Area there are thirty-seven Sites of Special Scientific Interest, including large areas of chalk grassland.
The grazing of sheep on the thin, well-drained chalk soils of the Downs over many centuries and browsing by rabbits resulted in the fine, short, springy turf, known as old chalk grassland, that has come to epitomise the South Downs today. Until the middle of the 20th century, an agricultural system operated by downland farmers known as 'sheep-and-corn farming' underpinned this: the sheep (most famously the Southdown breed) of villagers would be systematically confined to certain corn fields to improve their fertility with their droppings and then they would be let out onto the downland to graze. However, starting in 1940 with government measures during World War II to increase domestic food production and continuing into the 1950s, much grassland was ploughed up for arable farming, fundamentally changing the landscape and ecology, with the loss of much biodiversity. As a result, while old chalk grassland accounted for 40-50% of the eastern Downs before the war, only 3-4% survives. This and development pressures from the surrounding population centres ultimately led to the decision to create the South Downs National Park, which came into full operation on 1 April 2011, to protect and restore the Downs.
The downland is a highly popular recreational destination, particularly for walkers, horseriders and mountain bikers. A long distance footpath and bridleway, the South Downs Way, follows the entire length of the chalk ridge from Winchester to Eastbourne, complemented by many interconnecting public footpaths and bridleways.
The dip slope of the South Downs, as seen from Angmering Park Estate near Arundel (panoramic view).
The term 'downs' is from Old Englishdūn, meaning 'hill'. The word acquired the sense of 'elevated rolling grassland' around the fourteenth century. These hills are prefixed 'south' to distinguish them from another chalk escarpment, the North Downs, which runs roughly parallel to them about 30 miles (48 km) away on the northern edge of the Weald.