Exciting discoveries at Swartigill dig could include an Iron Age 'fridge'
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At the Swartigill Dig Open Day archaeologists displayed their many finds including jewellery and a construction that could be an early form of fridge.
Rick Barton, project officer with the Orkney Research Centre for Archaeology (Orca), along with colleague Martin Carruthers from the University of the Highlands and Islands, showed visitors around the areas the team have been excavating.
"The original perception was it could have been related to a [nearby] medieval farm," said Rick in reference to the initial investigation back in 2012 when Islay Macleod from Yarrows Heritage Trust (YHT) had contacted Orca after discovering part of a structure along the edge of a burn on the Thrumster Estate.
"It was quickly discovered there was a lot of Iron Age pottery amongst the structural remains that was fairly similar to that found within a nearby broch," added Rick. After two short seasons of digging at Swartigill in 2017-18, it was found that a lot of silt had flooded the site through the centuries and though it was hard to dig it helped ensure the preservation of the archaeology below.
"What we have at the site are a series of structures [and] we're still in the process of getting to the occupation layers to find when they date from. We do have some radiocarbon dates for the upper material which is at the first and second centuries BC."
The structures being uncovered seem to date from the same era as the Iron Age brochs that Caithness is famous for and suggest that a village of some complexity existed there for a number of centuries. Orkney archaeologist Martin Carruthers talked about the vast amount of work that had been done in the past to uncover and investigate brochs but he said it was all part of a "bigger picture" and there were other structures contemporaneous with the brochs of which there is "far less known about". The Swartigill excavation appears to be shedding some light on these lesser known buildings.
"Caithness has a remarkable archaeological record but which is very underdeveloped and not taken advantage of like in Orkney, The Western Isles and Shetland," Martin told the Open Day visitors.
The team have uncovered four separate elements in the area and say they have "tentatively" found a fifth. In 2019 an area of excavation showed what appears to be a short passageway or souterrain which may have had a ritual purpose or have been used as a larder to store food.
Martin said: "In Denmark there are a number of souterrains where there are channels underneath the floor and water flows along them. The theory is that it cooled the environment in there. When the souterrain is roofed over it develops quite a heat and that's not good for storing grain and suchlike."
He thinks the Swartigill site's souterrain may have been cooled by water flowing through small underground channels underneath its base and the most recent excavations appear to show water being diverted from the nearby burn for exactly that purpose. He agreed that it was not too far-fetched to think of it as an Iron Age fridge.
At the Open Day event, visitors were also shown some of the finds from the Swartigill dig which include fragments of pottery, a section of shale bangle, a piece of jewellery, whetstones, flints and burnt bone material.
There is little evidence of human bones at Swartigill and that is believed to be due to the acidic pH of the peat dissolving them but ironically burnt bone fragments are more likely to survive due to a change in their chemical structure after being incinerated. The intensity of the heat used to burn the bones suggest they come from cremations rather than cooking. The Orca team intend to send these fragments to a specialist laboratory for further analysis to ascertain if they are of human or animal origin.
"There are complex things going on through this period and people would have responded to climatic changes that could have led to flooding and the site eventually being abandoned," said Martin.
Director of YHT, Islay Macleod, called the Swartigill excavation "one of the most significant finds in the county since the Victorian era" and says there is evidence that the prehistoric settlement may be much bigger than originally thought.
"We know there is building work further up the burn to the west which is probably part of this same site and it appears to be a village."
The work is funded by local Foundation Scotland bodies along with the Lybster and Tannach Non-formal Learning Fund for YHT. More information on the work of YHT can be found at: www.yarrowsheritagetrust.co.uk/
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