A stone used by Neolithic people to sharpen stone axes, known as a ‘polissoir’, has been discovered in the Valley of Stones near Portesham in Dorset. Previously, most polissoirs in England had only been discovered buried in chambered tombs, placed there after they were no longer in use. This is only the second in situ polissoir to be discovered in England, the first having been discovered in Fyfield Down, Wiltshire, in 1962. (See CA 396 regarding a bedrock polissoir recently discovered in Scotland).
The Valley of Stones, where the polissoir was discovered, is an unusual site. Situated in a secluded valley, it was scheduled in 1970 primarily for an extensive field system of late prehistoric or Romano-British date; it also contains early enclosures and a geological ‘train’ of naturally occurring sarsen stones spread along the slope of the hill, from which it gets its name. It is believed that this natural scattering may have been the source for the stones used to construct several Neolithic monuments built in the surrounding area, including the Kingston Russell Stone Circle, the chambered tomb known as the Grey Mare and her Colts, and the Hell Stone (Helstone) burial chamber.
Recently, a survey of the sarsens located further up the valley, closer to the monuments, was conducted by Past Participate, an organisation championing community involvement in archaeology, with the aim of understanding more about how these sarsens may been used in prehistory. At the same time, as part of its protection as a scheduled monument and National Nature Reserve, Natural England was undertaking some scrub clearance in the base of the valley, which revealed some hidden sarsens. Volunteers from the conservation group EuCAN, who were working with Natural England, alerted Past Participate to this discovery, and two members of the team – Dr Anne Teather and Jim Rylatt, together with Dr Katy Whitaker from Historic England – then went to assess the newly revealed stones.
In brushing some leaf debris off one of the larger boulders during this analysis, a highly polished dish worn into the stone was revealed. It quickly became apparent to the team that this was not a natural occurrence and that this was instead a stone that had been used to polish tools, probably stone axe-heads during the Neolithic. In analysing the stone further, a pecked area on the margin of the polished dish became apparent, indicating that the surface had been redressed several times in order to roughen up the stone and make it suitable for further sharpening. These changes suggest that this polissoir had been well used over a significant period of time.
Following its discovery, the team from Past Participate approached Historic England, who gave permission for a specialist to take moulds of the polished surface in order to carry out further micro-wear analysis of the surface. It is hoped that this may identify the direction of polishing as well as more specific details about how the surface may have been reworked. A small excavation was also carried out earlier this year by Past Participate in order to see if any scatters of debris from axe-sharpening activities could be discovered, with the hopes that they might be able to determine the composition of the tools they were using. A 3D scan of the entire boulder was commissioned by Historic England, with an aerial photography and LiDAR study of the site being subsequently carried out by Aerial Survey and Landscape Archaeology Investigators in the Archaeological Investigations Team of Historic England.
While post-excavation work is still ongoing, preliminary analysis revealed a few Neolithic artefacts but no obvious signs of debitage. The excavation was partially hampered, however, by the fact that there was a large amount of colluvial soil that had moved down the slope, disturbing the natural stratigraphy of the site. The team from Past Participate hope that a second excavation next year will be able to reveal more evidence of the people who may have used this stone over 5,000 years ago. Historic England also plan to return to this site this autumn with a group of volunteers to further document the sarsens in the Valley of Stones as part of the ‘Missing Pieces Project’ (see CA 401 and 402).