Viking Link Proposed Converter Station Sites, Lincolnshire Geophysical Survey

The main aim of the geophysical survey was to provide sufficient information to enable an assessment to be made of the impact of any proposed development on any potential sub-surface archaeological remains and to aid in the site selection process for a new converter station as part of the Viking Link project. The survey was undertaken using four Bartington Grad601 magnetometry sensors mounted at 1m intervals (1m traverse interval) onto a rigid carrying frame. The system is programmed to take readings at a frequency of 10Hz (allowing for a 10-15cm sample interval) on roaming traverses 4m apart. These readings are stored on an external weatherproof laptop and later downloaded for processing and interpretation. The system is 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. MLGrad601 and MultiGrad601 (Geomar Software Inc.) software has been used to collect and export the data. Terrasurveyor V3.0.28.4 (DWConsulting) software has been used to process and present the data. Despite the presence of numerous cropmarks across the north, west and east of CS1, no anomalies of definite archaeological potential have been identified by the survey. Faint linear and rectilinear anomalies which correspond closely to the cropmarks have been interpreted as forming two possible enclosures and at least six possible ditches although no clear patterns are visible and interpretation is tentative. Numerous broad and sinuous anomalies have been identified throughout which correspond to subtle topographical variations. The anomalies are thought to be due to silt-filled channels within the former tidal flats and are natural in origin. It is concluded that there is insufficient magnetic contrast between the soil-filled archaeological features and the surrounding soils and superficial deposits for them to be detected with any clarity as magnetic anomalies. On this basis the archaeological potential of the two sites remains unclear but given the correlation between the geophysical anomalies, the contour data and the cropmarks within CS1 it is likely that the archaeological potential of this site remains higher than CS9.