EDO7852 - Winterbourne Abbas Corridor Geophysical Survey 2017-05

A magnetic survey, completed by TigerGeo Limited, was commissioned by RSK Environment to prospect the Preferred Cable Corridor for a proposed installation of underground cables for buried structures of archaeological interest. Survey was undertaken using an ATV-towed and GNSS-tracked sledge-mounted array of caesium vapour magnetometers and where this was not deployable, e.g. on some slopes, a handcart carrying a smaller array was used; to the same magnetic specification. The best results seem to be from thin soils over chalk, with chalk in general good for detection. Least good results were over mudstones, however, in these areas strong interference from overhead cables limited the utility of the data. A total of about 79 hectares was surveyed along approximately 8.8km of corridor, approximately 1km of which was not accessible, with a mean width of 60m. Each field was examined for slope and from that the likely location of colluvial build-up against field boundaries or within hollows. In no instances is there magnetic evidence for accumulated soils to be masking features that are magnetically detectable higher up the slope. There is circumstantial evidence for slight differences in magnetic character on hilltops but again this does not seem to have impacted upon the visibility of magnetic features. Anomalies due to features of likely archaeological interest are weak everywhere but contrast is locally variable. This will be due to changing magnetic properties or differential survival of remains. The range of archaeological feature types is fairly limited, being principally barrows, narrow ditches, ridge and furrow cultivation, large pit fills, also a broad track (possibly metalled). There is no obvious sign of settlement or industrial activity, though a possible funerary landscape is present in multiple locations. Many of the HER 'earthwork' monuments are not associated with a magnetic expression. Medieval field systems, where identified, do not appear to fit with these HER monuments. Although there is scatter of minor ditches throughout the corridor, there are no major ones. These small ditches do not appear to be clustered or have any foci. Where specific archaeological features have been identified, they tend to be present in groups, with prehistory and likely medieval landscapes both apparent.