THEY have been a part of Orkney for around 4000 years, when parts of Stonehenge were still being built.

But it is only in recent years that archeologists have begun to unlock the secrets of some of the long-forgotten artefacts along the shoreline of the Bay of Swandro on the isle of Rousay.

Now it has emerged the biggest concern among the experts is not from members of the public trampling over the 100 ancient artefacts this year that have been uncovered, but the natural elements of the sea.

Dr Stephen Dockrill, the leader of the excavation of the site which was discovered in 2010, has warned that the exposed site leaves it in danger of being destroyed by the sea at any time.

With the site's precarious location and the devastating impact of climate change, the expedition fears all their work to preserve the history may be destroyed by one large wave.

"We have come back with our fingers crossed every year since we have been working here," said Dr Dockrill of the University of Bradford.

"It's that one big storm that could take it all away."

It was in fact the sea that helped uncover the settlement back in 2010 when his colleague Dr Julie Bond noticed a few odd stones only just visible among the pebbles of the beach.

Since then, the seaward side has been eroded to reveal a sequence of levels which appear to date from the Middle Iron Age, through the Late Iron Age and all the way up to the period of Norse settlement on the island.

"This small portion of coastline that we have got is quite remarkable because it is like a layer cake where you can step up through time," explained Dr Dockrill.

The site has attracted experts and volunteers from as far as the City of New York University and the William Patterson University in New Jersey.

Dr Dockrill added: "They are coming in part for their training, but mostly because Orkney has perhaps some of the richest archaeology in the world.

"It gives them the experience of working on a complex archeological site where we have buildings that are still standing.

"That is a fantastic opportunity for any student of archaeology."

Since work began on the site in 2011, a geophysical study of the site has uncovered what is hoped to be an intact Neolithic Chambered Cairn, which could add further evidence of Orkney's rich ancient past.

Students from the university have also been undertaking a study of soil samples taken from the site.

Dr Bond explained that they were surprised that from the infill of a building that contained wall cupboards, the soil residues contained small fragments of glass, evidence for copper alloy casting and of iron smithing.

"The exchange of gifts, in terms of metal work, would have been very important," explained Dr Dockrill.

"It provided a means of maintaining the status of the person who lived here with his subordinates or with other people nearby."

The excavation team has also seen a lot of evidence of rising sea levels as a result of climactic change.

"We have been digging down below sea level in places which means we haven't found the original ground level, therefore we have actually seen quite a rise in sea level, probably at least several metres in the last thousand years," he added.

The team hopes to return next year provided they are granted permission to continue to excavate and they receive sufficient funding.

Dr Dockrill said: "What we are hoping to do over time is to give an idea of how people lived on the island, from the very first farmers, all the way through to Clearances."