The Knowe of Swandro is an archaeological site located on the Bay of Swandro on Rousay in Orkney, Scotland. The site consists of a 5000-year-old Neolithic chambered tomb, the remains of an Iron Age settlement that consists of Iron Age roundhouses and Pictish buildings, and two Viking age buildings. The Knowe of Swandro site is located directly on the beach and is being rapidly destroyed by coastal erosion.
In February 2024, the Knowe of Swandro project won the Current Archaeology Award for Rescue Project of the Year.
Location.
The Knowe of Swandro sits partly below the high tide mark under a boulder beach on the Bay of Swandro. The site was initially thought to be the remains of a broch since only the mound was visible, but the surrounding structures were discovered in 2010 by Dr Julie Bond when she spotted the worn, partially-buried uprights that formed part of a prehistoric building while walking along the beach.
Because of its location directly on the boulder beach, the Knowe of Swandro site is being rapidly destroyed by coastal erosion. The excavation has been focused on the seaward side, since it is at the highest risk of destruction by the sea. Despite the constant erosion, the archaeology has survived surprisingly well thanks to the boulder beach, which has provided some level of protection to the deposits and architecture below. Rising sea levels and an increase in the frequency and intensity of stormy weather systems as a result of climate change are exacerbating and accelerating the process. Additionally, there is an aquifer beneath the site contributes to erosion as water from the aquifer flows towards the ocean. As the sea has eroded the site a series of terraces, the seaward side of the site has been more significantly eroded and has been cut down to the lower and earlier layers. The terraces ascend landwards and later features from the upper levels of archaeology are preserved.
Work began in 2010 to record as much information and data as possible about the site before it is washed away completely. Excavation has continued annually since then. No excavation took place in 2020 and 2021 due to the COVID-19 pandemic, but excavation resumed in 2022. In addition to recording record data about the site for future research, the excavation will help give a better understanding of how tidal and storm damage have affected the site. This information can be used to develop management strategies for the Swandro site and other sites facing similar coastal erosion.
The entire site is elevated. The mound covering the circular roundhouse is about 3 to 4 metres high today, though the building itself was probably originally at least two storeys high. The central roundhouse is surrounded by a series of buildings from the Iron Age and later date. The entire settlement was originally surrounded by a stone-revetted ditch, which was built over by the first century CE.
The multiperiod nature of the site has led to complex courses of structural development. Smaller buildings were often built on top of older buildings which has led to a very three-dimensional site. Buildings were also modified over time, sometimes with larger, older buildings being modified to contain smaller, newer buildings.
The site.
It is likely that the site at the Knowe of Swandro is what remains of a larger, high status settlement. There is extensive evidence of complex and high-quality metalworking and an abundance of copper, lead, and iron in the area. Ready access to materials and technology necessary for high quality metalworking was likely a major source of power for sites like the Knowe of Swandro, as well as other sites in Orkney and Shetland.
Animal bones with evidence of butchering may be an indicator that feasting and similar high-status activities occurred in the settlement. Several pieces of Roman glass dating to the first century CE and Roman coins dating to the fourth century CE have been found at the site. Items such as these would have been valuable trade goods, but they also imply a greater level of connection than initially thought. The western coastline of Rousay and the coast of mainland Orkney on the other side of Eynhallow Sound were part of a major routeway through Orkney and a series of Iron Age settlements have been found along this route.
There is also evidence of extensive agriculture at the Knowe of Swandro. The botanical remains of cereals show that the settlement at Swandro had access to high-quality cereals in abundance, including bere, a kind of six-row hulled barley, and cultivated oats. There is evidence of grain processing areas and kilns used for drying cereals. The abundance of cereals is another factor that made settlements successful. Additionally, in the fields beyond the site are anthropogenic soils, which indicates long term human inhabitation and cultivation. The climate in Orkney was likely more mild in the Iron Age than it has been in recent history which would have lent itself to agriculture on this scale.
Surveying and recording methods.
The surveying of the site assists in the interpretation of ongoing excavation, and has been undertaken on the landward side of the site for this purpose. A number of surveying techniques have been utilized, including detailed earth resistance survey, electromagnetic survey, ground penetrating radar, and electrical resistivity tomography in surveys carried out by the University of Bradford. In 2019 extensive surveying was undertaken and these techniques were used to collect data at multiple depths to gain a better understanding of the site. Some of these techniques were more effective than others. The data given by the round penetrating radar was ambiguous, as the salinity of the soil negatively impacted the depth to which it could see. The data yielded by the ground penetrating radar did not give a solid measurement of the depth of the archaeology, but it did show that there were more buildings concentrated around the mound. Electrical resistivity tomography was extremely successful and was able to provide data about both the depth and the extent of the archaeology. The electrical resistivity tomography was able to confirm that the settlement was focused along the coastline. It also indicated the presence of water in lower archaeological layers, information that is vital to the management of the Knowe of Swandro and similar sites. The detailed earth resistance survey indicated that the large central roundhouse was surrounded by subsidiary buildings, which suggests the settlement was a nucleated village.
The recording of the remains of the settlement at the Knowe of Swandro is especially important because of its inevitable destruction via coastal erosion. The site is being recorded photographically with 3D scanning and with aerial imaging so that when the site is destroyed by the sea the permanent record can be used for future study. The lessons that are being learnt about the erosion processes and their effects on archaeology will help in understanding and mitigating the risks to similar sites. The lessons are important to record so the info can be referenced later as learning about site or studies in wider archaeological contexts allows for comparison between years, which helps in understanding how to interpret sites similar, dealing with coastal erosion. techniques used to record sites include archaeological drawings, photography, 3D scanning and aerial imaging.
Key structures.
The Knowe of Swandro site is made up of a possible chambered cairn and the remains of an Iron Age settlement that dates from between 1000 BCE and 1200 CE consisting of Iron Age roundhouses and Pictish buildings, and Viking to Norse age buildings.
Chambered cairn.
The most immediately visible feature of the Knowe of Swandro site is the eroding mound which covers the central roundhouse and a possible chambered cairn. The mound has been described as "the much-disturbed remains of a stony mound" in a publication account from 1946 and as a "mutilated turf-covered mount 1.5m. high, apparently containing the remains of a drystone structure" in a report from a field visit in 1967. At various points it has been thought to have been a Viking grave, a broch, or the remains of a roundhouse. The mound stands about four meters from the shoreline and is so close to the shore that the water level at high tide regularly reaches its outer walls.
In 2012 overlying beach was excavated by a team from the University of Bradford with students from City University New York and a circular structure formed by a series of concentric outer wall faces was revealed. At this point it was thought that the structure might be a Neolithic chambered cairn. The walls of the structure are more similar to the casement walls seen in Neolithic chambered cairns, which have a single outer face, rather than a broch, which has inner and outer walls. Each of the concentric walls of the cairn was backed by stone and had a midden core. It is now thought that some of the walls of this structure belonged to an earlier Iron Age structure, but that there may be a Neolithic structure at the core of the site. The 2012 excavations also revealed that the central structure was partially robbed at some point in its history. Further excavation has established that the robbery probably occurred in the Viking period and the disturbance was infilled with shillet and midden.
The seaward side of the cairn has been significantly damaged by erosion, but the main part of the site and the middens in the area have been protected by the seaward remains. As much of the cairn as possible is being excavated and recorded in order to be able to understand the archaeological sequence and record data for future study. In 2015 the cairn was completely scanned with a 3D scanner by Dr A Wilson of the University of Bradford and aerial photos were taken by Robert Friel and Lindsey Kemp. The site has been under active excavation for almost ten years, so it is possible to compare data from different years and see how erosion of the site has progressed in a relatively short period of time.
The rapid rate of erosion can be seen when comparing data from the 2012 excavation of the cairn to the data from the 2015 excavation season. In 2015 the section of the cairn that had been excavated in 2012 was re-excavated to investigate and record the level of damage caused by erosion. It was found that the outer walls of the cairn had been significantly eroded since they were first recorded in 2012. Much of the lower, seaward side of the outer casement wall had been removed by the sea thanks to heightened wave activity during the winter. The packing that was backfilled into the trench from the 2012 excavation had been badly eroded or replaced with beach material. Several large blocks from the lower section of the wall's facing had been completely removed, and some large stones that were angular at the time of the 2012 excavations were smoothed and rounded.
Structure 1.
Structure 1 is likely the remains of a large roundhouse. It is the earliest of the Iron Age buildings yet to be identified in the Knowe of Swandro Site. Very little remains of Structure 1, as is located on the beach and has been severely eroded by the ocean. The outer walls of Structure 1 are made of stone uprights and the floor is made of a single massive flagstone measuring about three meters in length. A mezzanine floor may have run around the perimeter of the inside of the building. There are slots carved into the flagstone that may have been the postholes for the uprights that may have supported this floor. Evidence of similar mezzanine floors dating to the Middle Iron Age was found at the Old Scatness site in Shetland, supporting this possibility.
Inside Structure 1 are the remains of a stone construction that is likely an oven of some sort. This oven is similar to an oven found in Structure 8 at Old Scatness. At this point hearths tended to be more for general use while ovens were for food production of a more specialized nature. The oven from Structure 8 at Old Scatness shows evidence that it may have been used to produce fish oil, and it is possible that the oven in Structure 1 at Swandro was used for a similar more specialized purpose. In addition to the oven, there is a large hearth.
Underneath Structure 1