Excavation
Date 6 June 2016 - 24 June 2016
Event ID 1025470
Category Recording
Type Excavation
Permalink http://canmore.org.uk/event/1025470
HU 327 848 (Grut Wells) and HU 326 902 (Beorgs of Uyea) The North Roe Felsite Project (NRFP) is a partnership involving University College Dublin, Shetland Museum and Archives, National Museums of Scotland, Queen’s University Belfast and the Implement Petrology Group. Building on the reconnaissance survey undertaken by Ballin, the project is addressing a central research issue for the Neolithic in Shetland (and Scotland), ie the role of a visually distinctive stone (reibeckite) felsite (Group XXII in the scheme of British stone implement petrology groups) which, during the Neolithic period, people transformed into polished axes and knives. The source is at North Roe, mainland Shetland where there is a well preserved major quarry complex. Here, blue to grey felsite dykes stand out against red granite bedrock. The NRFP is using archaeological and geochemical/petrological survey, a detailed GPS survey and targeted excavation, to try to identify the scale, character and date of the extraction processes. A project GIS integrates data from the quarry with analysis and mapping of felsite artefacts from across the Shetland archipelago held in museum and private collections, facilitating an integrated insight into the life path and role of these objects in Neolithic Shetland.
To date there have been three field seasons at North Roe, 2013, 2014 and 2016, collecting data at a range of scales at the quarry and beyond. In 2013 and 2014 portable x-ray fluorescence (PXRF) survey was carried out across the quarry complex, and on the collections of felsite objects in the Shetland Museum and National Museums Scotland which were also recorded in detail. This report focuses on the results of the 2014 and 2016 field seasons.
Survey in the 2016 season, 6–24 June, concentrated in two areas of the North Roe quarry complex. Within the scheduled monument (SM 890) at the Beorgs of Uyea detailed survey continued, building on initial survey in 2014.
This baseline survey is important in providing a detailed record of the surface deposits and evidence for quarrying at this key location. It is also documenting a range of features which appear to be associated with the quarrying activity, notably a series of over 60 standing stones to the SE of
the zone of quarrying and a major concentration of felsite blocks further to the E, at a distance of over 300m for the exploited felsite dykes.
The second area where detailed survey in 2016 was conducted was Grut Wells East. This is an area to the E of Grut Wells in the southern part of the complex where there is an important concentration of evidence for felsite working areas and related activity. Here, three felsite workshops were
identified including knapping areas with debitage, artefact deposition and the placement of felsite under propped granite boulders. This was first noted during the petrological/ geochemical survey of the complex.
Grut Wells Two trenches were opened at Grut Wells (Trench 1 and Trench 2). These were positioned across quarry pits (Pits 7 and 8) identified as running along the line of a probable quarried felsite dyke during survey in 2013. This survey also made it clear that the dyke was composed of
fine-grained felsite with dispersed pink feldspar phenocrysts.
Trench 1 measured 3.5m long E/W and 1m wide N/S and was positioned across the middle part of the quarry Pit 8. Trench 2 measured 9 x 1m across quarry Pit 7 from E/W. Here the ground surface sloped steeply to the E on the western side of the trench but was more gently dished towards the middle and E. Trench 2 was extended to 1.5m in width at the eastern end. Both trenches were mostly covered in peat with granite and felsite also present on the surface. The excavation of Trench 1 was completed in 2014. While excavation of Trench 2 commenced in 2014 it was largely excavated in 2016.
Trench 1 The peat cover here was very wet and claggy with deposits of felsite debitage inwashed from the current surface. The peat was at its deepest at the centre of the trench where it was 0.5m in depth from the ground surface, here there was no felsite. Below the peat there was a series of deposits related to quarrying activity. All contained felsite debitage of varying size concentrations and characteristics. One distinct deposit was a series of large, angular, granite boulders running NNW/SSE across the centre of Trench 1. These large boulders are presumed to be the result of removal of granite outcrop close to the felsite dyke. The weight of these boulders meant that they sank into the deposits below, creating a diffuse boundary between the fills in the central area of the trench.
Iron pan deposits formed across the surface of some fills. Two cuts/recuts were recognised in the trench. The granite boulders mentioned above formed part of the fill of the later of the two cuts. This later cut was made into granitic sand with significant quantities of felsite. At the eastern end of
Trench 1 this sand was initially thought to represent the top of the subsoil. But in the light of the excavation results from Trench 2 (see below) is now interpreted as probable upcast/ fill on to the western side of the dyke, covering the quarried dyke surface, which was not exposed during the excavation of Trench 1. Current interpretation is that the western side of the dyke lies just E of the eastern end of the trench. It also appears that the initial quarry pit/extraction area extended further W than the western edge of the trench, implying that it was over 3.5m in width.
Trench 2 The initial trench measured 9 x 1m and was set out across Pit 7 from E/W. This was extended by 0.5m on the eastern side so that the trench was 1.5m in width N/S from the felsite outcrop in the centre to the eastern end of the trench. Like Trench 1, the surface of Trench 2 was largely covered with peat, which was waterlogged in places. The depth of the peat varied considerably across the trench, and it contained a small quantity of inwashed lithics. Quarry rubble with felsite and granite had built up on the near vertical slope on the western side of the trench There were a series of contexts relating to the quarrying of the felsite dyke, which was revealed by excavation at the centre of the trench. The dyke was 4.4m in width (and extended beyond the eastern edge of the trench) and from the top of the dyke as exposed in the centre of the trench it was 1.8m in depth. It was composed of a series of felsite blocks, separated by fault lines in the felsite, which predominantly ran along an axis 40° NW/SE of the main alignment of the dyke. Quarrying was focused on extracting blocks from the dyke. Evidence of this was demonstrated in the scarring and nibbling of the surface of the dyke. Distinct quarrying activity could be recognised on either side of the dyke. A definite quarry pit excavated into granitic sand and granite outcrop along the western margin of the felsite dyke was recognised. This was 1.4m in width at what is the definite rock surface, 0.6m in width at the base. It was dug to a depth of 1.0m into solid granite. As excavated the overall dimensions of the cut, including the extraction of felsite is 3.6m in width with a depth of 1.72m. On the eastern side extraction appears to have extended from the surviving highest point of the dyke to beyond the eastern edge of the trench. The deposits within Trench 2 represented backfilling episodes of the extraction areas. They varied from loose, unconsolidated masses of felsite flakes to compact sandy clays containing worked granite and felsite, relating to the various phases of the quarrying process. There was a notable density of finds in Trench 2 with a total of 65 finds being recorded, all relating to the working of the felsites, including axe/adze roughouts, hammerstones, wedges and cores.
Beorgs Of Uyea Targeted excavation was carried out at the Beorgs of Uyea (SM 890) under the terms of the scheduled monument consent at the western end of the zone of exploitation. The focus here was an excavation trench, Trench 1 (5.3 x 2m) across a quarry pit, with felsite outcrop visible in the centre. This dyke is composed of spherulitic felsite with banding evident at the margins of the dyke. The work aimed to understand the primary stages of quarrying, to place this in the context of the detailed survey being undertaken at the Beorgs of Uyea, and to compare and contrast this with the evidence from Grut Wells. Trench 2, a second small excavation area (2 x 2m), focused on what appears to be a fallen felsite standing stone in an area where there is a concentration of large felsite blocks E of the major zone of quarrying and dyke exploitation. This was discovered during initial survey in 2014. The relationship of these standing stones and blocks with the Neolithic quarry activity is an important issue in terms of understanding the significance of the landscape.
Trench 1 The position of Trench 1 was chosen to provide a cross-section of a clearly defined quarry pit, with a block of the quarried dyke in the centre of the trench. Surface material, in the form of granite and felsite blocks and debitage, was scattered predominantly in the E, W and N of the trench with the dyke exposure in the centre-south. There was peat and vegetation cover over much of the trench, extending out from the central dyke material. While definite quarry pits could be recognised to the E/N and to the W of the dyke, the excavated deposits in Trench 1 were very shallow compared to Grut Wells and comprised mainly unconsolidated quarried felsite blocks and debitage (all of it spherultic and banded), with some granite. Despite the granite/felsite margin being diffuse the edges of the quarry pits could be recognised. In both cases they appeared to continue to the N. The eastern trench was 1.6m in width and 0.5m in depth. The western trench is better defined and was also 1.6m in width and 0.5m in depth. Where peat accumulated around loose
stone it provided a matrix for some deposits. One context towards the bottom of the pit on the western side of the dyke contained finer felsite flakes and may represent a later stage in the working of the felsite for the production of roughouts.
It is clear from the excavation that there were a number of phases of quarrying represented. Quarrying appears to have begun on the W side. With the tilting of the dyke block after it was undercut there was further quarrying on the E and northern side. The last phase of quarrying was of the current W face of the dyke. The base of the quarry pits was uneven quarried felsite with sand deposits indicating that the pits may have been left open after initial quarrying.
Trench 2 was a 2 x 2m area around a suspected fallen felsite standing stone, located 290m E of the eastern-most dyke in the zone of exploitation. It was located in an area of deposition of felsite blocks and occasional definite felsite standing stones (further W there is a major concentration of granite standing stones). Trench 2 was deturfed and the felsite block was found to be sitting within what may be a deliberate setting composed of granite boulders, although the terrain here under the peat cover is a granite boulder field making definition of features quite difficult. The felsite block did appear to have been placed as a standing stone. It appears that it fell to the N, as indicated by damage on the NE side of the block and the presence of impact shatter flakes on the granite in this area. The stone was not lifted and the area was recovered.
Ballin, TB and Davis, V 2012: Shetland: North Roe (Northmaven parish); survey and evaluation. DES 13 (2012), 167
Cooney, G, Ballin, TB, Davis, V, Sheridan, A, Markham, M, and Megarry, W 2013: Shetland Islands: Beorgs of Uyea/ Grut Wells, North Roe, Northmavine parish; Survey; First season of North Roe Felsite Project (Making an Island World: Neolithic Shetland). DES 14 (2013), 174–175
Archive: UCD School of Archaeology (currently), National Museums Scotland/Shetland Museum and Archives (intended)
Funder: National Geographic Society (Global Exploration Fund, GEFNE147–15), University College Dublin, College of Social Sciences and Law and National Museums Scotland
Gabriel Cooney and Joanne Gaffrey – UCD School of Archaeology, University College Dublin
(Source: DES, Volume 17)
