EDO8130 - Admiston Farm, Puddletown and Athelhampton; geophysical survey 2022

The cart-based gradiometer system used a Carlson BRX7 RTK GNSS instrument, which receives corrections from a network of reference stations operated by the Ordnance Survey (OS). Such instruments allow positions to be determined with a precision of 0.02 m in real-time and therefore exceeds European Archaeologiae Consilium recommendations (Schmidt et al. 2015). The detailed gradiometer survey was undertaken using a Bartington 601-2 dual magnetic gradiometer system. This instrument has four sensor assemblies fixed horizontally 1 m apart and mounted on a non-magnetic cart. Data were collected with an effective sensitivity of 0.03 nT at a rate of 10 Hz, producing intervals of 0.15 m along transects spaced 4 m apart. Project Results: The detailed gradiometer survey has been successful in detecting several anomalies of varying magnetic properties. Across the site, several areas of increased magnetic response have been identified, likely associated with modern agricultural practices. The larger amorphous areas of disturbance are expected to be associated with fertilisation. Whilst the smaller, more isolated areas are likely the result of a build-up in magnetic material, similar to instances visible on satellite mapping over the site. Several ferrous anomalies have also been identified in the form of a metal pylon, a modern service and metallic material present in the site’s field boundaries. The remains of historic cultivation have also been recorded in the form of medieval ridge and furrow.