THE secrets beneath a mysterious burnt mound are being uncovered in an archaeological dig in West Dorset.

The mound of burnt material, probably from the Bronze Age, was spotted eroding from the cliff face at Seatown by local archaeologist Anthony Pasmore who alerted the National Trust.

It is being investigated by archaeologists in the hope of better understanding the 3,000-year-old feature.

The feature is said to be disappearing fast as the sea cuts into the soft sands and clays at the cliff edge.

Buried under more than a metre of sand and soil, the mound isn’t visible on the cliff top and it was only the erosion of the cliff edge which has brought it to light.

The National Trust regional archaeologist Martin Papworth said: "This is the first burnt mound found in West Dorset. They are more common in the Midlands but nobody is sure what they were used for.

"We don’t know if this burnt mound was something used for ritual feasting, a sweat lodge or an industrial site but we hope to find enough clues to shed a little more light on it. We’ll take samples as we dig down through it to understand it better."

The site is buried so deeply because of the way fine sand washes down to the bottom of slopes and also from windblown sand on the coast. This deep burial hides the archaeology until it becomes exposed in the cliffs.

It was originally much further inland, since the Dorset coast has been eroding at an average rate of roughly 0.25-0.5 a metre a year, the burnt mound would have been almost a mile from the coast when originally used.

During the dig samples will be taken at different levels in the hope of finding the clues which explain what the mound was used for.

Charcoal can be collected for radio carbon dating and pollen found in the mound will help to show the plant life nearby at the time – especially whether it was a wooded area or a grassy hillside.

The Trust archaeologists will also carry out a geophysical survey to see if any other features show up in the field.

Mr Papworth added: "There are a lot of large blank areas on the archaeology map of West Dorset. But with some of the projects we are doing in the area, we are starting to fill in a few of them and we hope this site will reveal something of interest."

The Seatown dig is part of a year-long series of events celebrating the 50th anniversary of the Neptune Coastline Fundraising campaign, set up in 1965 to protect the coast from the threat of development and look after it for ever for the nation.

Over the last 50 years, public and partnership support have raised over £65 million for the campaign, enabling the National Trust to safeguard 775 miles of coastline across the England, Wales and Northern Ireland (300 miles of which are in the South West).

Events have been taking place at National Trust places across the South West all this year as part of the Coastal Festival, from mass beach cleans attended by over 400 volunteers earlier in March, to a series of coastal Bio-Blitz events, a Big Beach Picnic and the dig at Seatown.

For more details on the South West Coastal Festival, go to www.nationaltrust.org.uk/swcoast and also check out a film of the South West coast for inspiration of places to visit http://bit.ly/coastfilm