Survey work in the Loch of Stenness (Ortkney, Scotland) has revealed what could be a massive prehistoric monument lying underwater to the south of the Ring of Brodgar. The underwater 'anomaly' has come to light in a project looking at prehistoric sea level change in Orkney. The project, The Rising Tide: Submerged Landscape of Orkney, is a collaboration between the universities of St Andrews, Wales, Dundee, Bangor and Aberdeen.
     Although it is tempting to speculate that the ring-shaped feature, which lies just off the loch's shore, is the remains of a henge or perhaps a prehistoric quarry, at this stage the project leaders are urging caution. Orkney-based archaeologist, Caroline Wickham-Jones, a lecturer at the University of Aberdeen, explained: "The preliminary results are suggesting that there is an unusual 'object' in the shallow water just off the shore, but more work is needed before we can identify it or even confirm whether it is a natural, perhaps geological, feature, or something man-made."
     Dr Richard Bates from the School of Geosciences, St Andrews University, added: "The character and size of this feature - approximately 90m in diameter - are about the size of the main Ring of Brodgar. If it turns out to be artificial, the massive anomaly has to predate the influx of the sea into the Stenness Loch basin."
     When prehistoric Orcadians started to build the stone circles in Stenness, the landscape would have been much different to what it is today and the sea would have been about a metre below current levels. Even then, the impact of the rising water in the Loch of Stenness was a bit slower. "We think there was a gradual incursion of the sea over time, preceded by a number of storm events that saw seawater crash over the rock lip and begin to form what was to become the Loch of Stenness," said Ms Wickham-Jones.
     As well as the Stenness Loch, the project has also focused on Hoy, Hoxa and the Bay of Firth. In the latter, the surveys have revealed how the landscape was transformed from the start of the Mesolithic period (c.7000 BCE), when the "bay" was dry land, to the late Neolithic/Bronze Age (c.2000 BCE), when sea water had filled in the lower-lying areas leaving Damsay as a tidal island.
     Dr Martin Bates, of the University of Wales, commented: "Survey has identified a possible lake site in the Finstown basin before the sea flooded the area, and this may have been a focus of activity during the Mesolithic. In future, diving at the margins of this lake might reveal evidence for such activity".
     Ms Wickham-Jones added: "Archaeologists study what's there, but sometimes it's more interesting to ask what's not there. The early Neolithic tombs around the bay for example: where are they? Many other early Neolithic tombs in Orkney - such as Unstan - are found near present sea level, on low-lying land. Were the earliest tombs around the Bay of Firth built on land that has since been covered by sea?"

Edited from Orkneyjar (3 October 2011)