The Fillingham Project overview - Geophysical Surveys
Two geophysical surveys were carried out in Fillingham prior to excavation, to determine if the remains of an Anglo-Saxon church were in fact present in the village. The location of these two surveys is shown on the map below. A resistivity survey was chosen, as this type of geophysical survey is regarded as the best for locating stone structures (Merrony, 1995). Resistivity surveys measure the resistance soil has to an electric current, which is dependent on the level of moisture in the soil. Archaeological features can be detected if their level of resistivity is different from that of the surrounding natural soil. Stone features, such as walls, roads and foundations, are generally drier than the surrounding soil, and are shown on resistivity surveys as high resistance anomalies (Clark, 1990).
Resistivity surveys are unlikely to reveal burials, as the features are too small to be detected, especially when taking readings on a 1m grid (David, 1995). Occasionally cist burials can be detected on a 0.5m grid using a resistivity survey, but as such an intensive survey is very time consuming, it was not felt worthwhile given the size of the paddock and the time constraints. Other evidence already strongly suggests the presence of burials in the field. The paddock survey was primarily concerned with trying to detect any structures in the area, with the hope of detecting the ground plan of an earlier church.
The survey of the orchard was carried out a couple of weeks after the survey of the paddock. Given the small size of the survey, and the possibility that the cemetery discovered in the garden and to the east of Lakeside cottage extended into the orchard, readings were taken on a 0.5m grid. The mobile probes were set at 25 cm apart, to give a representation of features between 0.4 and 0.6m deep (David, 1995; Merrony, pers. comm., 2000), as following the interpretation of the paddock survey it was felt that shallower readings would be more appropriate for this area.