Buried secrets revealed at Dinas Dinlle coastal fort

August saw the first ever archaeological excavation to be carried out at the iconic north Wales prehistoric coastal fort of Dinas Dinlle, owned by the National Trust. The hillfort, which is mentioned in the Welsh legends of the Mabinogi, is being dramatically cut by coastal erosion. Between 20m and 40m of the western side has been lost since 1900, and the entire fort could be gone within 500 years.

More than 50 local community volunteers helped excavate the roundhouse at Dinas Dinlle. [Image: Gwynedd Archaeological Trust 2019]



The constantly eroding soft cliffs have long made it a challenging site to survey. In June, however, the cliff edge was studied by a small team of archaeologists from the EU-funded CHERISH project (see CA 324), which examines climate change and coastal heritage in Wales and Ireland. This was followed in August by a three-week evaluation excavation by Gwynedd Archaeological Trust within the fort and in fields to the south, with 50 volunteers from the local community taking part. As the diggers stripped away the turf and topsoil, they were faced with tonnes of sand overlaying the archaeological layers and features, in some places around 1.5m deep. once removed, a series of deeply buried stone structures was revealed. By far the most impressive discovery was a monumental stone-built roundhouse a few metres from the cliff edge. Measuring 13m in diameter, it is thought to be one of the largest ever found in Wales. The stone walls themselves are striking, measuring over 2.4m thick, with well-built faces. Its date has not yet been confirmed beyond the few sherds of roman pottery found close to the walls.

The excellent preservation of the stone walls of the roundhouse suggests that the initial sand deposition at the site may have been rapid, probably during periods of major storm activity. CHERISH is now using luminescence dating to determine when, and how quickly, the archaeology was buried.

Meanwhile, the full story of the dig will emerge in the coming months, as the post-excavation work is completed. Dr Toby Driver, an archaeologist with the CHERISH Project, said: ‘The dramatic discovery of an extremely well-preserved prehistoric or roman roundhouse, buried beneath clean windblown sand, seems to confirm that climate change has always been a feature of life at Dinas Dinlle.’

Look out for a feature on this CHERISH project in a future issue of CA.

This news article appears in issue 356 of Current Archaeology. To find out more about subscribing to the magazine, click here.