Sea level results lead to radical rethink over World Heritage Site landscape

Sue Dawson taking a core sample from the Stenness loch.

A radically different picture of the prehistoric landscape around Orkney’s World Heritage Site is beginning to emerge – a landscape which perhaps didn’t feature the Stenness and Harray lochs.

Preliminary results from an archaeo-environmental project indicate that, prior to 1500BC, the Stenness loch was an area of wet marshland surrounding small pools or lochans.

The Rising Tides project is looking at past sea level change and prehistoric settlement around Orkney. At the helm is local archaeologist Caroline Wickham Jones and Sue Dawson from the University of Dundee. Since 2006, the pair have gathered core samples, initially focusing on the Stenness loch and Echnaloch, in Burray.

Analysing the remains of the tiny creatures known as diatoms, preserved in the sediments of both sea and loch, the experts can pinpoint when the sea around the islands reached its present level. The diatoms preserve a record that shows both rise and fall of sea level. By taking cores of material from various sites, it is possible to examine the changes between fresh water to marine diatoms, and, therefore, when and how sea level changed.

Picture: Caroline Wickham Jones

Cleaning a sediment core from Voy, on the Stenness loch.

Sue Dawson explained: “Two dates have now been obtained which start to give a more precise idea of the period at which the sea reached present level. In both cases gyttja – organic sediment – has been dated. This is associated with gradual changes in assemblages, which reflect the changing salinity of the water and thus encroaching sea level.”

The Echnaloch samples gave a date of 2340 – 2570BC, while at Voy, in Stenness, the date is between 1440BC and 1270BC.

Compare this to the estimated construction dates of the Ring of Brodgar (c2500BC-2000BC) and Standing Stones of Stenness (c3100BC). By the time the Stenness loch was fully established, the Ring of Brodgar had been standing for approximately 500 to 1,000 years. Click here for World Heritage Site timeline.

Sue explained: “The Echnaloch date relates to a change to freshwater conditions from marine with the closure of the marine embayment after the emplacement of the barrier, a storm beach, along which the present day road runs.

“Voy lies at the inland extremity of the loch of Stenness and the date relates to a change to marine and brackish conditions from freshwater or lagoonal.”

These single dates give an initial idea of when sea level reached present levels around Mainland Orkney.

Picture: Caroline Wickham Jones

A sample core showing the variations in the type of sediment.

The time lag between Voy and Echnaloch is likely to be due to the different geographical positions and sheltered nature of Voy, which is behind a shallow rock lip that may have allowed freshwater conditions to prevail for longer at the north-western edge of the loch.

The project now plans a more intensive programme of dating at these and other sites in order to refine interpretation.

Caroline Wickham Jones commented: “Archaeologically, the dates are important because they indicate just how much the landscape of Orkney has changed since the World Heritage sites were built, around 5,000 years ago.

“Environmental reconstruction from coring suggests that, rather than being connected to the sea, the Loch of Stenness comprised a lake with reed beds at the time when the Ring of Brodgar and the Stones of Stenness were first built. Something similar to the Loons, in Birsay, today.”

“While the sites were in use the sudden ingression of sea into the Loch of Stenness as it reached the level of the rock lip at the Brig o’ Waithe must have been a notable event.  The subsequent flooding of the Stenness basin took place over the later life of the monuments making this an area of dynamic environmental change which must have impacted on the lives of those living in the area.

“Around Orkney relative sea levels would have been lower for much of the Neolithic, raising the possibility of submerged Neolithic sites and landscapes in the shallow seas between the islands.”

In June, the project plans further coring in the deeper Seatter embayment – nearer to the Brig o’ Waithe – to refine the history of the loch of Stenness.

This, it is hoped, will answer another major question – if the Stenness loch wasn’t there to push water through into the neighbouring Harray loch, did it exist also? Or was the Harray loch another area of marsh?

The dates immediately raise a number of questions over the Ness of Brodgar monuments. If there was no loch, for example, the theory the stones were floated to their present site goes out the window. Another casualty is the idea that the Standing Stones of Stenness and Ring of Brodgar were erected where they are because of an interaction between the land, lochs and sky.

However, archaeologist Nick Card of the Orkney Research Centre for Archaeology (ORCA) feels the lack of lochs would not necessarily have lessened the significance of the Ness to the Neolithic builders. If anything, he suggests, it may have enhanced it.

“If we had these two marshy, boggy areas on both sides of the Ness, not only would that mean the Ness was more pronounced, in relation to the low lying landscape around it, but it would remained a ‘liminal’ place, bordered by two ‘no-go’ areas.

“The fact remains that the monuments were constructed in a natural amphitheatre and right through the middle of it there’s a natural walkway or causeway, running north-west to south-east.”

He added: “It really is very interesting, and the ingress of water into the Stenness basin is actually much earlier than I had thought. But it raises many questions and avenues for further investigation. With the existing marshy area to the north of the ring, around the Dyke o’ Sean, was there a time when the Ring was surrounded by bog? Perhaps standing on an ‘island’ and bordered by marshland.”

“It’s a primary strand of evidence,” said Nick, “but we do need more dates, and more evidence, which I hope the project will be able to supply in the future. It’s going to alter the way we view the landscape surrounding the Ness of Brodgar in the Neolithic, and maybe into the Bronze Age.”

The project was funded by Historic Scotland, The Crown Estate and Orkney Islands Council.

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