Geophysical Survey at Witney BESS, Oxfordshire

The survey was undertaken using four Bartington Grad601 sensors mounted at 1m intervals onto a rigid carrying frame. The system was programmed to take readings at a frequency of 10Hz on roaming traverses (swaths) 1m apart. These readings were stored on an external weatherproof laptop and later downloaded for processing and interpretation. The system was linked to a Trimble R12 Real Time Kinetic (RTK) differential Global Positioning System (dGPS) outputting in NMEA mode to ensure a high positional accuracy for each data point. MLGrad601 and MultiGrad601 (Geomar Software Inc.) software was used to collect and export the data. Anomaly GeoSurvey v1.12.3 (Lichenstone Geoscience) and QGIS v.3.34.6 software was used to process and present the data respectively. The survey has recorded anomalies indicative of modern and older agricultural activity (modern ploughing and ridge and furrow cultivation), as well as those of modern and natural origin. Two parallel linear anomalies have been interpreted as of uncertain origin, most likely also due to agricultural activity although given the proximity of known archaeological remains an archaeological origin cannot be dismissed. The extent of a pronounced area of variable magnetic background, attributed to changes within the sub-soil and superficial deposits, has also been clearly identified in the centre of the site. The number and variety of the anomalies detected indicates that there was probably sufficient magnetic contrast, for the detection of sub-surface archaeological features, if present, notwithstanding the limitations of magnetometer survey to identify certain types, sizes and periods of archaeological features. However, it should be noted that the generally low amplitude of the recorded anomalies allied with the potential 'masking' effect in the area of geological variation suggests a generally low magnetic contrast leading to a reduced anomaly resolution. It is therefore considered that the results give a reasonable indication of the archaeological potential of the site which on the basis solely of the results of the survey is assessed as low.