EDO6466 - Stonehills Mine, Portland; gradiometer survey 2018

A gradiometer survey was carried out on behalf of Terrain Archaeology prior to topsoil stripping by Albion Stone. Due to cost and time constraints the survey was restricted to the 6.5 ha area of the field where there would be most subsurface impact. A Bartington Grad 601-2 fluxgate gradiometer was used and the results analysed by Geoscan Geoplot 3.00v. The survey grid comprised 138 contiguous whole and partial 20m squares. There were two discrete concentrations of positive and negative magnetic anomalies to the north and towards the southwest of the area respecting major negative linear anomalies running north-south across the field. There was also a southeast-northwest trend of weak parallel linears. The readings suggested organic banks and ditches, possibly a strip field system with visible slight earthworks in the field. There was a scatter of non-linear anomalies across the whole area some of which may have been modern ferrous disturbance but could indicate archaeological cut features/deposits associated with anthropogenic activity. The report concluded that there were demonstrable archaeological features in two areas of the site representing at least two major, perhaps multiple phases of agricultural activity.