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 (Illus 4). These readings were stored on an external weatherproof laptop and later downloaded for processing and interpretation. The system was linked to a Trimble R8s Real Time Kinetic (RTK) differential Global Positioning System (dGPS) outputting in NMEA mode to ensure a high positional accuracy for each data point. Headland Archaeology (UK) Ltd was instructed by Ian Pick Associates Ltd on behalf of The Executors and Trustees of Captain Elwes (c/o Balfours) (the Client) to undertake a geophysical (magnetometer) survey covering approximately 7 hectares on land at Low Risby, North Lincolnshire. This report will be submitted as part of a planning application proposing the construction of an irrigation reservoir at the site. The results of the survey will also inform future archaeological strategy, if required. The survey has recorded linear ditch type anomalies which may locate two enclosures of uncertain date in the eastern half of the GSA. However, an archaeological origin is not certain. Other recorded anomalies are indicative of recent ploughing, boundary removal and possible localised mineral workings. Geological anomalies are also ubiquitous across the GSA. Overall, the archaeological potential of the GSA is assessed as low except in the immediate vicinity of the two possible enclosures where it is assessed as low to medium.
Matt Berry (Sat,) studied this question.