Llangorse: a unique Irish crannog in Viking Age Wales

Dr Alan Lane, Senior Lecturer
Cardiff University

The crannog in Llangorse Lake is one of the most remarkable archaeological sites in Wales. A unique example of a crannog, its construction is precisely dated by dendrochronology and its destruction by historical documentation. 

 It was first discovered and dug in the 1860s by two local antiquarians but the absence of datable artefacts and the failure to find similar sites in Wales or England led to scepticism about the identification. Archaeologists don’t like unique sites as they challenge our ability to get comparative meaning from them. But in the early 1980’s I visited the site and was amazed to find oak planks sticking out of the water and apparently encircling the site just as the 19th century excavators had claimed. 

I realised it was what it claimed to be – a crannog or artificial island settlement. With a small Cardiff team, Ewan Campbell and I cut pieces of oak for dendrochronological dating which showed that the trees from which the planks were split had been cut down some time after the mid- 9th century AD, indicating the crannog was built in the Viking Age.  

At this point we were joined by a team from the National Museum of Wales led by Mark Redknap, an experienced underwater archaeologist, and a series of water and land explorations of the site were launched. This work with student and professional teams ran intermittently from 1989 to 2004. The whole of the exposed shore and adjacent waters of the island was examined but only limited areas could be excavated. Post-excavation analysis has taken decades and involved many different specialists leading to publication in January 2020 of the definitive report. 

The combined underwater survey and land excavation has allowed us to understand its process of construction, to date it, and place it in precise historical context.  

At the core of the crannog is a small natural peat island which was enclosed by a series of oak plank palisades. It began as small D shaped enclosure some 20 metres from the north shore of the lake. An oak plank palisade enclosed a brushwood raft, pinned down by oak beams.  

This supported a stone mound and probably turf and soil. This initial enclosure was expanded several times till it was about 35m by 45m across. An entrance probably lies on the northern edge of the site where posts for a bridge ran out to the shore. 

Erosion of the site has eaten into the southern half of the island and removed any surface structures from the small areas we were able to excavate.  

Tree ring analysis of the oak palisades encircling the site show that the site was constructed in the 890’s.  This places it in the middle of the Viking wars when Welsh kingdoms were faced with threats from competing English, Viking and Welsh kings. The detailed Anglo-Saxon accounts of the decades around 900 allow us to see movement of Viking armies through Wales and provide a context for the crannog construction. Remarkably the Anglo-Saxon Chronicle tells us that in 916 Brecenanmere, the English name for the lake, was destroyed by Aethelflaed, the Mercian queen, and the queen of Brycheiniog was captured. It seems clear that the crannog was a short-lived royal site. 

The erosion of the site stripped the surface deposits but dumped objects and food remains in the lake. These finds allow use to see something of the status and life of the crannog. This site was not a farm but was receiving food supplied probably as food rents as recorded in the medieval Welsh laws. Large quantities of well-preserved animal bone show pigs, sheep, and cattle were being supplied to the site but the remarkable quantity of wild species suggest that deer hunting and feasting was an important part of the aristocratic behaviour of the residents. 

The artefacts in iron, copper alloy, bone and stone indicate domestic occupation, but a few finds are exceptional and confirm its royal identification.  Two objects, a fragment of religious ‘house shrine’ and a penannular brooch are probably of Irish origin. 

However the most remarkable find was the fragments of a linen, silk embroidered tunic decorated with animals and birds. This find required many years of highly skilled conservation work and analysis to understand and preserve it, and it has rightly been regarded as one of most remarkable archaeological discoveries of any period from Wales.

The crannog remains unique in Wales and it seems that crannogs did not become a feature of the Welsh cultural landscape. But the crannog helps give credence to the origin legend of the kingdom of Brycheiniog which claims part Irish descent for Brychan from whom the kingdom is named. The site is remarkable evidence of the genuine links with Ireland and the dramatic, but poorly recorded, history of the Viking Age in Wales. 

You can also read more about Llangorse in the latest issue of Current Archaeology!

2 thoughts on “Llangorse: a unique Irish crannog in Viking Age Wales”

  1. […] most remarkable archaeological sites in Wales – as explained in Alan Lane’s post this morning (do go look at it!). It is a unique example of a crannog, which also is able to give us some unique insights into […]


  2. […] Llangorse Lake or Llyn Syfaddan in Welsh is named for its shape, the saddle. In medieval times it was noted for its miraculous properties.  About 4-miles in circumference it is the largest natural lake in south Wales. An interesting reconstructed 8th Century crannog sits on the lake. it is opposite the site of the original. Remarkably the Anglo-Saxon Chronicle tells us that in 916 Brecenanmere, the English name for the lake, was destroyed by Aethelflaed, the Mercian queen, and the queen of Brycheiniog was captured. https://archaeologyandconservationcardiff.com/2020/06/12/llangorse-crannog/ […]


Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s