In late March 2016 Suffolk Archaeology carried out two Geophysics open days at Garden Field, Sutton Hoo, allowing visitors to the famous National Trust site to learn about how such surveys are carried out. Two types of equipment were used, a magnetometer and a magnetic susceptibility meter …
In late March 2016 Suffolk Archaeology carried out two Geophysics open days at Garden Field, Sutton Hoo, allowing visitors to the famous National Trust site to learn about how such surveys are carried out. Two types of equipment were used, a magnetometer and a magnetic susceptibility meter.
The project, which was jointly funded by the National Trust had two aims. One was to simply survey the field for archaeological remains, the second was to establish if such a drop-in project was suitable for visitor participation as a part of the Sutton Hoo experience.
Garden Field is situated in the grounds of Tranmer House, close to the famous Anglo-Saxon Sutton Hoo ship burial and immediately to the northwest of the visitors centre. Archaeological fieldwork undertaken over the last thirty years on Garden Field has most significantly recovered remains of a rare imported artefact known as the ‘Bromeswell Bucket’, which is of eastern Mediterranean origin dating from the 6th century and was discovered in the southeastern corner of the field.Parts of the field had previously been surveyed by caesium vapour magnetometer and so this phase of prospection was targeted at those areas not previously covered, with the addition of a magnetic susceptibility survey over the whole field.
The magnetometer survey was eventually carried out twice, once by Suffolk Archaeology staff and once by members of the public visiting the National Trust site. This proved to be important as the visitor’s magnetometer datasets proved to be too 'noisy', due to the high degree of ferrous material present on volunteers clothing affecting the sensitive magnetometer’s sensors! Nevertheless the volunteers enjoyed walking the 20m grids and getting to grips with the principles and methods of carrying out a detailed magnetometer survey.
The survey recorded a range of geophysical anomalies. Positive linear trends indicative of potential Bronze Age, Iron Age or Romano British field subdivisions and a droveway, thermoremanent responses indicative of at least one kiln type anomaly, and a plethora of discrete pit type anomalies were of particular archaeological potential. Two areas of magnetic disturbance and sparse isolated dipolar responses may also be of an archaeological derivation. One broad geological anomaly records the potential remains of a former river channel of the River Deben. A dipolar linear trend delineating a service run and negative linear trends of agricultural origin reveal evidence of modern site activity.
The magnetic susceptibility survey was carried out by both Suffolk Archaeology staff and site visitors (the equipment not being affected by ferrous material in their clothing). Readings of the level of magnetisation within the volume of earth beneath the sensor were taken every 10m within a grid laid out over the entire field. Higher magnetic readings are commonly indicative of settlement type activity - for example fires, or in this case potential human cremation activity believed to have taken place during the Anglo-Saxon period.
The magnetic susceptibility meter survey revealed that peaks of higher soil magnetisation were predominant in the eastern half of the existing field, these higher readings are more indicative of settlement type activity. Lower readings were recorded in the western half of the field where potential colluvial deposits located on the side of the slope may mask deeper lying areas of cultural enhancement.
Suffolk Archaeology would like to thank the National Trust for their co-operation and help in organising the project.