Archaeology 2006

Following a chance conversation about archaeology with John Holbourn who comes from the island of Foula, the subject of geophysics was raised. He asked what I knew about it and I gave him a short description of the way we go about things. He said that there was a good case for a geophysical survey on the island and did I know of anyone who might be interested in doing it? Thinking of our own extreme survey team, I half jokingly said "Yes I might". At this point he started to look serious and said "Really? Are you sure? It would be all expenses paid". And so in May 2006 a team comprising Jayne Lawes, John Oswin, Owen Dicker, Bridget Hetzel, Margaret Nuth and myself journeyed north to this small island while John Holbourn went by car and ferry to meet us when we arrived.

Foula is situated about fifteen miles west of Shetland out in the Atlantic. It is about three miles long and two miles wide and has a population of twenty six. We were intending to do most of our surveying in an area known as Harrier, which is farmed by John's niece where, because of an island tradition concerning an early Christian Chapel and a Norse graveyard (backed up by finds of numerous artefacts there), we would look for mediaeval and prehistoric remains. Other surveys were to be a ridge on a hillside called Da Heights and an area known as Springs, which was about to be lost to the sea.

The survey at Harrier went well although the terrain was difficult, so we were unable to survey as much as we had intended. The weather, although cold (May there is like February down here), was very kind to us apart from one incredibly wet afternoon when we were forced to stop surveying. The main features which the Harrier survey revealed were several circular anomalies which may well be prehistoric hut circles and enclosures and some straight and rectangular anomalies which were possibly of later date.

With time running out we started our survey of Da Heights (Figure 1). This is a ridge, covered by peat with a lot of stones visible on the surface (Figure 2). We did Resistivity and Magnetometry surveys which revealed evidence of an extensive ditch and a stone structure buried below the present 'planticrub' (a stone-built protected seedbed). Bridget, who had been studying the stones on Da Heights, was certain that there appeared to be a circular formation, so on our last day she and Jayne did an EDM survey of the stones while the rest of us surveyed Springs. Later that afternoon we were analysing our results and preparing to give a presentation to the islanders. The EDM did indeed seem to confirm that there was a circular structure; however further study would have to remain until we got home.

Figure 1. The original EDM results

Figure 2. The stones at Da Heights

On our return, we started to analyse our results in greater detail and were amazed to find that what we had thought to be a ring of stones seemed to resolve itself into two concentric structures (Figure 3). These structures, however did not seem to be exactly circular. Research by John Oswin turned up the work of the archaeologists Professor Alexander Thorn and Dr John Wood, who had analysed many such structures and found them to be based on an egg shape, such as the ring at Borrowstone Rig in Cumbria (Figure 4). These egg shapes fitted our structure very neatly, but I was worried by the mathematics that Thorn claimed was used in their construction involving the use of right angled triangles.

Figure 3. The distribution of surface stones at Da Heights.

I found that, instead of using a 3, 4, 5 right angled triangle, there was an altogether simpler way of constructing the same shape. This simply involved drawing two circles where the radii were in the ratio of 5 (the length of the hypotenuse) to 8 (the combined length of the hypotenuse and the shorter of the two other sides).

Figure 4: Wood's diagram of Borrowstone Rig and the same diagram
using two circles.

Applying this to the structures at Da Heights, this ratio fitted very well with both the inner and outer rings. Not only that, but it is possible to make a case for the ratio of the inner ring to the outer ring also being 5 to 8. We also discovered that the geophysics results show the probable existence of further stones which would fit within this structure.

Having determined that the Da Heights structures do seem to have this shape, they consequently have an axis. I was wondering what this axis might be and decided to compare it with solar events on Foula. Imagine my amazement when I discovered that the axis points towards the midwinter sunrise. Further research (in an, as yet, unpublished paper, The Timing and Alignment of Solar Events on the Island of Foula, Shetland Islands, UK, Keith Turner,) shows that the orientation of midwinter sunrise at these latitudes has varied by less than 2 degrees of arc in the last 4000 years, making it entirely plausible that, if this is indeed a prehistoric structure, then it could have great significance.

Because of our limited surveying time, the majority of the analysis has been done since we left the island and the results would need to be verified. In particular, we would need to resurvey the entire area, this time recording the size and shape of the stones. The surface of Da Heights is covered with peat which is probably several feet thick. We need to determine the depth to which these surface stones go and, if they have been sunk into the bedrock, then there can be no denying that this is indeed a man-made structure.

At this stage there is still the possibility that this is some form of natural feature, but the weight of evidence is so great that the emphasis would now be on disproving the theory rather than proving it. In any event it will certainly be fun finding out.

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Bridget's Circles

The BACAS geophysics team who spent a week in the Shetland Isles made an interesting discovery, to be investigated in 2007. By John Holbourn

My lifelong love affair with the island of Foula began when I was five. The war had just ended when we went north from Oxford to Shetland through a khaki-strewn transport system with timetables all askew. Sixty years later I drove back from Wiltshire to Shetland, my car filled with BACAS equipment topped off with a carefully strapped down folding wheelchair. Aged five, I had been blissfully unaware of the "weather permitting only" vagueness of Shetland travel. Now it was foremost in my mind—would the very small Foula ferry take my car and the equipment into Foula before the team arrived by air? Keith took one look at a photograph of the ferry and changed his mind about taking his car! Would the team make the connection between the Shetland airport at Sumburgh and the Inter Island TingwaJl airstrip in time? Would the scourge of Shetland summer flights – fog – stay away? What were the team going to make of wind-lashed horizontal rain; would they cower indoors waiting in vain for the sun to shine? How come such a worrier was rewarded with no transport hitches, nearly constant sunshine and only one afternoon of rain, culminating in pleas from everyone, "Please come again, we've not had such a fine spell of spring weather for years!"

I had left Shetland, I thought, for the last time in 2001, seduced into retirement by southern England's soft and gentle climate. That I changed my mind was down to two people: a young archaeologist, Helen Bradley, completing her university education through two seasons work in Foula (2004 and 2005) appraising the island's archaeology, and a not-quite-so-young Keith Turner aiding and abetting me by getting BACAS interested. Now, a year later, I have lost track of who is trying to persuade whom into doing further work in the Isle. Perhaps I can sum it up by repeating what John Oswin said to me on my return to Wiltshire with the equipment, 'John, that trip was better than any holiday!' Music to my ears!

The BACAS geophysics team demonstrate stoicism on the cliff edge.

I find it hard to convey an impression of Foula and its community to anyone unused to remote places. Mostly I'm met with blank stares—a place with no shop, no pub, no doctor, no trees, no this, no that. Where even today, in winter, there may be no ferry for a month. Almost certainly the last place in Britain where subsistence agriculture was practised, where the only wheel until the 20th century was a spinning wheel. For centuries some of the men sailed the worlds seas, yet never brought home a wheel? To me, a complex mystery. Some of the best blacksmiths, carpenters, tailors, shoemakers that you could hope to meet. You name it, they could do it, make it, with what was to hand in the Isle, yet still everything was carried on the back. A place that looks very bleak and bare, yet provided a living and left an archaeology that litters the landscape, except where the peat has buried it

Which brings us to 2007 and a part of the Isle covered with peat, but with many stones protruding. Thanks to Bridget and Jayne's last minute EDM survey in May, the possibility of a unique stone circle complex has been revealed, two concentric ovoid circles with the long axis pointing to the winter sunrise and a number of stone walls radiating outwards. All on a hilltop but skewed to one side of it. Why two circles? Was the first one found to be too big, too small? How deep is the peat? What is it covering, undetected by the geophysical surveys? Why did I never see all this beneath my feet? If it is all what we think it might be, how is that going to affect the Isle? Will the archaeological world begin to take an interest? Could it be that important or is it just a gleam in our eyes and a lot of wishful thinking? Questions, questions and yes, you are right, I have caught the archaeological bug! Let's hope June 2007 reveals all!

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