Crannog in Llangorse Lake

Cadw's description

Summary description and reason for designation

The following provides a general description of the scheduled monument.

The monument consists of the remains of a crannog, an artificial island, dating to the late 9th century, the early medieval period. It is the only crannog in Wales and consists of a small tree covered island 40m from the north shore of the lake. In summer the site comprises a stony roughly rectangular mound 30m N/S by 40m E/W protruding up to 0.8m above the water line. In winter the site is often completely submerged. The site was initially identified in 1868 when the lake levels dropped exposing oak planks and piles. Investigations by Henry and Edgar Dumbleton revealed tool marks on the tips of the planks and layers of imported stone forming the centre of the island. They compared their findings to those from lake villages in Europe, recognising that the island was a built structure, and suggested a prehistoric date. Later scholars compared the island to the prehistoric and medieval crannogs of Ireland and Scotland. The discovery, in 1925, of a log boat 400m to the east of the crannog lead Sir Cyril Fox to postulate a late Iron Age/Romano-British date for both the boat and the crannog. In 1988 a team from Cardiff University surveyed the island and took samples of the timber for dating which revealed it to have been constructed between AD860 and AD906.

Subsequent excavations by Cardiff University and Amgueddfa Cymru revealed that the crannog had been constructed in phases over a short period of time. The oak planks forming the palisade had been driven into the lake bed to a depth of over 1m and probably protruded above the waterline by around 2m, encircling the area of the crannog. The main body of the island consisted of a wooden raft overlain by stone and clay. The raft was constructed using bundles of roundwood branches that were held in place using large oak beams and pegs. This was overlain by a mix of clay and boulders which formed the solid surface of the crannog.

Finds from the site comprise high-status artefacts as well as evidence for horses and hunting, the preserve of the wealthy. Fragments from a copper-alloy reliquary, the terminal ends of several penannular brooches, part of a drinking horn, combs, glass beads and dress ornaments, together with the remains of a silk embroidered linen tunic have allowed the site to be identified as a Royal residence associated with the Kings of Brycheiniog. The crannog was destroyed by fire in around AD916, possibly by Æthelflæd, daughter of Alfred the Great of Mercia. An event recorded in the Anglo-Saxon Chronicle states that she destroyed ‘Brecenanmere’, identified as the Llangorse crannog, and captured the King’s wife and 33 others.

The monument is of national importance for its potential to enhance our knowledge of elite medieval sites, and for its association with recorded historicl events. It retains significant archaeological potential, with a strong probability of the presence of associated archaeological features and deposits. The structure itself may be expected to contain archaeological information concerning chronology and building techniques, together with a strong probability of environmental evidence.

The scheduled area comprises the remains described and areas around them within which related evidence may be expected to survive.