The survey was undertaken using four Bartington Grad601 sensors mounted at 1m intervals (1m traverse interval) onto a rigid frame. The system was programmed to take readings at a frequency of 10Hz (allowing for a 10-15cm sample interval) on roaming traverses (swaths) 4m 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.3.28.5 software was used to process and present the data respectively No anomalies of archaeological potential have been recorded by the survey. All the anomalies are interpreted as of geological, agricultural, or modern origin with the findings limited to several sinuous low magnitude trends, which likely identify former channels and/or tidal creeks, areas of magnetic disturbance caused by disturbed ground and pylon bases and linear trends resulting from field drains or modern ploughing. No anomalies indicative of salterns have been recorded. The results of the survey reflect the findings of previous magnetometer surveys in and around the substation and consequently the overall archaeological potential of the site, based solely on the magnetic data, is assessed as low.
Webb et al. (Mon,) studied this question.
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