New questions raised by geophysics surveys of Brodgar peninsula

Picture: Craig Taylor

Looking north to the Ness of Brodgar, from the Standing Stones of Stenness.

For centuries, scholars and antiquarians have had their own theories about the activities that took place in Orkney’s Neolithic heartland – the World Heritage Site covering the Ness of Brodgar, in Stenness.

From druid enclosures to ancestral monuments, each era had its own ideas about the Neolithic ceremonial centre. Writing on the subject in the 1980s, archaeologist Graeme Ritchie cautioned that: “We have been at pains not to imply that we know more than we do.”

This statement remains true today. Despite the advances in archaeological knowledge, technique, and technology, there is still very little known about the area.

But this looks set to change, with the continuation of an Orkney Archaeological Trust (OAT) project to use magnetometry to scan the entire Brodgar peninsula. The archaeologists will be looking for clues as to what lies beneath the turf and to put the known sites into a wider context.

Magnetometry is the technique of measuring, and mapping, patterns of magnetism in the soil. Ancient activity, particularly burning, leaves magnetic traces that show up even today when detected with the right equipment. Buried features such as ditches or pits, when they are filled with burnt or partly burnt materials can show up clearly and give us an image of sub-surface archaeology.

So far, 45 hectares around the World Heritage Sites have been scanned, the results of which make interesting viewing. But far from unlocking the secrets of Brodgar, archaeologists have found that the scans have raised as many questions as answers.

The scans carried out so far make impressive viewing. The entire Brodgar peninsula is covered in anomalies that indicate that there was once considerable activity there – although the exact details of this remain tantalisingly unclear.

“If this is all related,” said Nick Card of Orkney Archaeological Trust, “then we’re looking at what could potentially be the largest Neolithic settlement or ceremonial sites in Britain.”

The idea that the Ring of Brodgar and its environs was regarded differently – or stood apart – by the Neolithic Orcadians also seems to be strengthened by the geophysics results so far. They clearly show a lot of activity around the Standing Stones of Stenness, the Brig o’ Brodgar and house of Lochview right up to Brodgar Farm. At this point, however, from a landscape rife with anomalies, there comes an almost clinically defined point where activity ceases.

Although some fields north of Brodgar Farm have yet to be scanned, it does appear, from present evidence, that there was a distinct cut off-point – an invisible boundary the area’s inhabitants did not want to cross. Does this mark the start of a symbolic shift in the perception of the landscape? Or is there a more mundane reason – a field or territorial boundary perhaps? Despite all the questions the scans raise, the evidence to provide answers awaits ‘ground truthing’ of the geophysics by excavation.

Nick explained: “We’re still assessing the geophysics results which will allow us to focus our attention on particular research questions.

“Although a lot has been written about the World Heritage Site, there’s a lot still to be discovered, not only in terms of structures and monuments, but how they all inter-relate with each other. It is hoped that the excavation of some of the geophysical anomalies will provide answers as to how all of these sites functioned with each other.”

As reported at the time, a chance discovery on the Ness in April this year revealed solid evidence of one of the geophysics anomalies – a stone dwelling almost exactly halfway between the Standing Stones of Stenness and the Ring of Brodgar.

The structure was found to be remarkably similar to the Neolithic structure at Barnhouse, a short distance away. At Barnhouse, this “double-house” has come to be interpreted as being that of a chief or person of authority. Whatever its original purpose, the structure was different from its contemporaries in that it was the only house at Barnhouse that was not superseded – in other words, it stood throughout the entire life of the village. All the while, houses around the structure – now referred to by the rather unglamorous name of Structure Two – were being knocked down and rebuilt.

Barnhouse Structure Two

Barnhouse Structure Two

After the preliminary excavation the structure was covered over again. OAT are now planning to revisit the site to refine the earlier magnetometry scans, this time running over the area with resistivity scan.

Soils and rocks conduct electrical currents differently based on their moisture content, clay content and porosity, among other factors, so resitivity scan allows the archaeologists to build up a picture of disturbed ground, such as ditches or foundations. Within the next few weeks the Trust hope that the new scans will allow them see a clearer picture of the settlement.

County archaeologist Julie Gibson added that an investigation into soil surrounding the site is hoped will help answer why the building is found in the middle of a huge area of magnetic anomalies.

“The further study of this structure and the area around it could offer an insight into the relationship between ritual and domestic life in the Neolithic, which is probably not encountered at many other locations,” she said.

The scanning work around the World Heritage Sites is ongoing, with other areas due to be covered at the end of October.

This will include an area to the north-west of Maeshowe, where aerial photographs indicate the presence of a large enclosure. The geophysics scans should clarify the nature of this site, showing whether it is perhaps the remains of another Neolithic henge monument or perhaps a settlement.

In 2004 the investigation of the remaining gaps of the massive scanning project will continue, with the area between Brodgar Farm and the Ring of Brodgar earmarked for investigation.

The Brodgar scanning project is funded by Historic Scotland and Orkney Islands Council. Geophysics work will be undertaken by GSB Prospection from Bradford.

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