EDO6775 - Geophysical Survey Report of Land at Lower Road, Stalbridge 2020

EDO number requested by Leanne in advance of work. 'Magnitude Surveys was commissioned to assess the subsurface archaeological potential of a c.5.4 ha area of land at Lower Road, Stalbridge. The survey was completed using a Bartington Instruments Grad-13 Digital Three-Axis Gradiometer with a traverse interval of 1m and a sample interval of 200Hz reprojected to 0.125m. Positional referencing was through a multichannel, multi-constellation GNSS Smart Antenna RTK GPS outputting in NMEA mode to ensure high positional accuracy of collected measurements. The RTK GPS is accurate to 0.008m + 1ppm in the horizontal and 0.015m + 1ppm in the vertical. Magnetic and GPS data were stored on an SD card within MS’ bespoke datalogger. The datalogger was continuously synced, via an in-field Wi-Fi unit, to servers within MS’ offices. This allowed for data collection, processing and visualisation to be monitored in real-time as fieldwork was ongoing. A navigation system was integrated with the RTK GPS, which was used to guide the surveyor. Data was collected by traversing the survey area along the longest possible lines, ensuring efficient collection and processing. The fluxgate gradiometer survey was successfully completed across the site. No anomalies suggestive of significant archaeological features have been identified. Evidence of agricultural activity has been detected in the form of possible unmapped former field boundaries, a possible former small stock enclosure abutting one of the boundaries of the survey area, and modern ploughing regimes. Anomalies undetermined in origin have been recorded as well and may relate to agricultural or natural processes; however, an archaeological origin cannot be entirely ruled out. Anomalies natural in origin have been identified, which are likely the result of soil variations produced by slope formation processes. Concentrations of small ferrous anomalies were identified which likely relate to debris on or close to the ground surface. Two buried services have also been detected. The impact of modern activity on the results has been identified as broad ferrous anomalies from extant metal fencing and field boundaries.'