Parc Cwm long cairn (), also known as Parc le Breos burial chamber (), is a partly restored Neolithic chambered tomb, identified in 1937 as a Severn-Cotswold type of chambered long barrow. The cromlech, a megalithic burial chamber, was built around 5850 years before present (BP), during the early Neolithic. It is about seven miles (12 km) west south–west of Swansea, Wales, in what is now known as Coed y Parc Cwm at Parc le Breos, on the Gower Peninsula.
A trapezoidal cairn of rubble – the upper part of the cromlech and its earth covering now removed – about long by (at its widest), is revetted by a low dry-stone wall. A bell-shaped, south-facing forecourt, formed by the wall, leads to a central passageway lined with limestone slabs set on end. Human remains had been placed in the two pairs of stone chambers that lead from the passageway. Corpses may have been placed in nearby caves until they decomposed, when the bones were moved to the tomb.
The cromlech was discovered in 1869 by workmen digging for road stone. An excavation later that year revealed human bones (now known to have belonged to at least 40 people), animal remains, and Neolithic pottery. Samples from the site show the tomb to have been in use for between 300 and 800 years. North-West European lifestyles changed around 6000 BP, from the nomadic lives of the hunter-gatherer, to a settled life of agricultural farming: the Neolithic Revolution. However, analysis of the human remains found at Parc Cwm long cairn show the people interred in the cromlech continued to be either hunter-gatherers or herders, rather than agricultural farmers.
Parc Cwm long cairn lies in a former medieval deer park, established in the 1220s CE by the Marcher Lord of Gower as Parc le Breos – an enclosed area of about , now mainly farmland. The cromlech is on the floor of a dry narrow limestone gorge containing about of woodland. Free pedestrian access is via an asphalt track leading from the park's entrance, which has free parking for 12–15 cars about from the site. Parc Cwm long cairn is maintained by Cadw, the Welsh Government's historic environment division.
History
From the end of the last ice age (between 12,000 and 10,000 BP) Mesolithic hunter-gatherers began to migrate northwards from Central Europe; the area that would become known as Wales was free of glaciers by about 10,250 BP. At that time sea levels were much lower than today, and the shallower parts of what is now the North Sea were dry land. The east coast of present-day England and the coasts of present-day Denmark, Germany and the Netherlands were connected by the former landmass known as Doggerland, forming the British Peninsula on the European mainland. The post-glacial rise in sea level separated Wales and Ireland, forming the Irish Sea. Doggerland was submerged by the North Sea and, by 8000 BP, the British Peninsula had become an island. By the beginning of the Neolithic (6,000 BP) sea levels in the Bristol Channel were still about lower than today. Historian John Davies has theorised that the story of Cantre'r Gwaelod's drowning, and tales in the Mabinogion of the water between Wales and Ireland being narrower and shallower, may be distant folk memories of that time. The warmer climate caused major changes to the flora and fauna of Great Britain, and encouraged the growth of dense forest that covered 80–90% of the island.