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Cover of British Archaeology 84

Issue 84

September/October 2005



We found new megalith, say dowsers

Good news for Silbury Hill - if money is found

Orkney dig first to date gold and amber jewellery

Objectors scent victory at Stonehenge

Exeter bids for new students

Stone plaque is first neolithic face in over a century

In Brief


Saving the H Blocks - Long Kesh/Maze: An archaeological opportunity
The artefacts of fear...and why we should preserve them - Laura McAtackney questions Northern Island proposal

Cemetery requiem for a lost age
Roberta Gilchrist reveals extraordinary Christian practices

Lake rescue
Saving Llangors Crannog, a unique medieval Welsh royal island, from erosion

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Headlines from the CBA office.


ISSN 1357-4442

Editor Mike Pitts


Rescuing Llangors Crannog

The only known historic lake settlement in England and Wales was steadily eroding. Earlier this year archaeologists were part of a team that set out to save it. Gerry Wait, Simon Benfield and Colin McKewan report

Llangors Lake (Llyn Syfaddan in Welsh), though never more than 7m deep, is the largest natural lake in South Wales, covering some 150 hectares. The rare ecology has made Llangors a site of special scientific interest and a special area for conservation. The remains of two logboats have been found in the lake (in 1925 and 1990), and about 40m from the northern shore is a tiny artificial island known as Ynys Bwlc, built in the 10th century AD.

This "crannog", unique in England and Wales, had been eroding for some time, thanks to wind-driven waves, and, in recent years, pleasure-boat wakes. The lake (maximum wave fetch 1.2km) is exposed enough to generate waves of up to 500mm, and considerable fluctuations in water level from summer to winter exacerbated the threat. Responding to this, a programme of conservation and excavation was completed in February.

High Status

Earlier excavation and historical records throw light on this unusual site. In 1989–1993 Mark Redknap and Alan Lane from the National Museum of Wales excavated both "dry-land" on the crannog itself, and underwater, and recovered many and varied artefacts.

The crannog was made of brushwood tied in bundles and placed on the lakebed. Hardwood beams and a ring of radially-split oak piles held down this buoyant "foundation". Red sandstone boulders had been placed over the brushwood creating a stable platform about 25m across. No original floor or surfaces survived the erosion, and the nature of any superstructure is speculative except for small joint fragments.

Remains of a remarkably fine, high quality textile, some of it embroidered in a style imitating soumak (weft-wrap weave) were found in material eroded from the island's western side. In these same silts was a bronze strap-hinge from a small portable reliquary of 8th–9th century date. The enamel, millefiori and glass decoration, insular in style and technique, are most closely paralleled in Ireland. Other finds included a pseudo-penanular brooch terminal and quantities of animal bones and worked timbers.

The hinge and textile are very high status artefacts, suggesting a link between political and ecclesiastical presences on the crannog quite unlike the Irish crannogs. Tree ring dating indicated tree felling CAD889–893, and construction very soon thereafter. A distinctive destruction horizon was observed, marked by layers of charcoal and charred timbers.

Historical records suggest it is likely the crannog once supported a royal hall, linked with a monastery near the modern parish church. The oldest reference is among the Llandaff Charters, indicating a royal presence at Llangors in the 8th century ad. One of the charters is a claim by King Awst of Brycheiniog, who gave Llan Cors and its territorium (estate) to Bishop Euddgwy. The bounds of the territorium, described topographically, match the present Llangors parish. The churchyard of St Paulinus in Llangors village is circular in plan – often a hint of an early monastic origin. There are three early Christian monuments, one inscribed in Latin "the cross of Gurci. Bledrus [set it up]", dating to the 10th–11th centuries.

The Abingdon Chronicle, a manuscript of the Anglo-Saxon Chronicles, records that in AD916 (when the king was Tewdwr ap Elised, king of Brycheiniog) Aethelflaed, Lady of Mercia, sent an army into Wales to revenge the murder of Abbot Ecgberht. The Mercian contingency destroyed Brecenamere and captured the king's wife and 33 others. The attack on the mere probably refers to the crannog, and the destruction horizon may relate to this event.

A crannog is a characteristically Irish type of site, and this, with the luxury Irish style artefacts, has aroused some speculation. It is interesting to note that the origin-legend for the kingdom of Brycheiniog claims descent from an eponymous founder Brychan, son of a Welsh mother Merchell and an Irish king Anlach. This legend may be supported by 5th–6th century ogham-inscribed stones in Brycheiniog.


Two local antiquarians, Edgar and Henry Dumbleton, were the first to recognise the island as a crannog, inspired by the English publication of Ferdinand Keller's excavations of Swiss "lake villages" in 1866, and by excavations of Irish crannogs. Their plan is useful for comparison today.

Shoreline erosion was recognised in 1987, and subsequent annual surveys by Redknap and Lane indicated very considerable changes to the island since the Dumbleton brothers' visit.

In 1998 Gifford Ltd was appointed toundertake a feasibility study for alternative engineering solutions to the erosion. A design was submitted to the Heritage Lottery Fund, but though it was approved, HLF was unable to help because the island is privately owned.

The design was revised for Cadw, who consented to both the engineering works and limited archaeological investigation. In 2004 a detailed study revealed yet again that erosion was active and significant.

In summer 2004 Maritime Archaeological Research Consultants Ltd (MARC) undertook small excavations for Gifford on the southern shore of the crannog, in areas not investigated in 1993.

The underwater investigations were conducted by teams of two divers with a supervisor, working from two boats. A water dredge acted as a vacuum cleaner to remove excavated materials, depositing the sediment and any objects into a sieve where they were collected and sorted. Areas were divided into 1m square boxes for excavation and finds plotting.

A midden (rubbish pile) was found at the outer limit of one trench, where the original island occupants dumped their discarded food remains. These included butchered pig, cattle and sheep bones, the shells of many fresh water mussels and fish bones. Notable artefacts included a cast copper alloy drinking-horn end, a section of a copper alloy bracelet or torc, and two sections of stone finger rings. All finds were recorded and given to the National Museum of Wales for conservation and display.


Finally, in February 2005 the erosion protection scheme was executed. It has three main elements: a main offshore bund, shoreline armour, and stone fill between, all underlain by geotextile to prevent the new structures from settling into the lakebed.

This design created a lagoon between the bund and the island. Any waves large enough to pass over the bund without being "tripped" are stopped by the shoreline armour. The stone fill protects the bed of the new lagoon. It is anticipated that the lagoon will silt up and provide a good environment for reed beds (as are seen elsewhere in the lake) which will act as further defence against wave action. A production line was set up on site for more than 2,000 sandbags. These protect the historic timbers from damage and help preserve them in an anaerobic environment.

Archaeologists from marc carried out a watching brief to ensure that there was no damage to timbers and to recover any new artefacts. Simple garden canes were used to mark historic timbers and guide the placement of rock-armour.

The engineering contractor, Quantum (GB) Ltd, using J McCarthy Ltd as their principal subcontractor, constructed a temporary jetty using ballasted Unifloat pontoons. Sandbags, the terram membrane and the rock armour were taken from this jetty out to the island by a flat-topped pontoon made by locking four small sections together. All the pontoon sections, and the tug, had to small enough to be trucked into Llangors Lake along narrow lanes.

Asecond Unifloat barge carried a 360° excavator which was used to place the rock and stone and, in deeper water, to lower the sandbags from a palette. This plant barge was moored offshore using two spud piles driven temporarily into the lake bed. It was moved around the perimeter of the works as they progressed from the northwest to the northeast in three major phases, dictated by the reach of the 360° machine.

For each section, terram was laid, sandbags placed to hold it in position, and then the lines of historic palisades and piles were sandbagged.

When this was complete, an infill of small stone grit was placed into the gully between the sandbags and around the palisade planks. The medium grade stones were then laid around the sandbags. Finally, the largest grade of rock armour was positioned by the engineer along the summer lake level beach line, and a further rock bund laid around the outer limits of the crannog. The process was then repeated in the next section around the island. Almost all of the work was done by hand.

Conditions were not ideal, as the weather turned extremely cold midway through the programme. We continued to lay rock despite ice forming on the lake. The snow and bitterly cold winds added to the discomfort of the crew working on site, and interfered with the work schedule, so weekends were used to make up days when necessary, enabling the project to be completed ahead of schedule.

The water level in the lake was also a factor. At the start of the work the lake was approximately 500mm above normal summer level. With the subzero temperatures and lack of rain, the lake level dropped rapidly, limiting access by the working pontoons due to their draft requirements.

Working on the lake for an extended period allowed us the privilege of observing the daily routine of the birds on and around the island. The three main players were the swans, geese and a small flock of cormorants that gathered on the island's big willow tree every evening as the work team left. From the shore the birds looked primeval, being long, black and quite large. The geese could be heard in a nearby field early each morning, then a vast flock would fly by and descend onto the lake. Each evening they would gather again on the lake, taking off in great numbers to return to the field for the night. The swans also flew by us, giving a display of their skills of lowlevel flight. Some quite inquisitive – and even proprietorial – individuals came close, begging for food and carefully observing us whilst we worked in the water.

Cadw grant-funded the Llangors Crannog works to the Brecon Beacons National Park and gave scheduled monument consent: without their financial and enthusiastic practical support, the protection could not have been achieved. The project team included Peter Dorling (Brecon Beacons National Park archaeologist), Sian Rees (Cadw), Gerry Wait and Simon Benfield (Gifford Consulting Engineers & Archaeologists), Colin and Leslie McKewan, James Vessey, Louise Munns (Maritime Archaeological Research Consultants/MARC), and Jim Goodfellow and Dave Donaghy (Quantum (GB))

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