EDO5623 - Three barrows west of Badbury Rings, Shapwick; geophysical survey 2010

The National Trust commissioned a geophysical survey on land at Badbury Rings. This was in advance of the installation of rabbit proof mesh in the barrows to prevent the local rabbit population from further damaging the barrows. Therefore a fluxgate gradiometer (magnetometry) survey had to be carried out prior to the laying of mesh, as this would have adversely affected the survey results. The area was divided into 20m grids aligned north-south/ east-west. 9 grids were surveyed using the resistivity meter, and 16 using the fluxgate gradiometer. Resistivity was carried out using a Geoscan RM15 resistivity meter. The twin probes were set 0.5m apart and readings were taken at 1m intervals in 1m traverses, and therefore 400 readings were taken for each 20m grid. The survey was carried out in a zigzag mode starting in the south-west corner and walking north. The magnetometry was done using a Geoscan FM36. Readings were taken at 0.5m intervals in 1m traverses. This led to 800 readings per 20m grid. This survey was carried out in parallel. The resistivity survey was clearer, despite the conditions being relatively dry. This showed the effects of burrowing on the mounds, in particular on the north-west side. The fluxgate gradiometer survey indicates that the Roman road side bank runs under the mound but the original quarry ditch is circular rather than the oval current shape of the barrow mound.