Geophysical Survey in the Deben Valley 2021

Featured image: volunteer conducting a magnetometry survey

Over the course of several weeks in 2021, 13 volunteers from the Suffolk Archaeological Field Group conducted a magnetometry survey on a ploughed field in the Deben Valley, as part of the Rendlesham Revealed project.

The aim of the survey was to look at a new area in the Deben Valley to help us understand the wider landscape context of the area around Rendlesham and Sutton Hoo.

Before the survey started, we looked at the cropmarks on the field, which showed a probable prehistoric ditch system, overlayed by a more grid-like Romanised system. Several artefacts previously found over the years on the field indicate continuous activity from the Iron Age to the 5^th century.

The geophysical survey results show extensive activity over a wide area, including structures, kilns, ditches and ponds. Interestingly, there was evidence of possible occupation and a succession of rebuilding. Ditches and circular features indicate possible Iron Age round houses and settlement.

Text boxes and an image of the geophysics results — geophysical survey results with annotated interpretation

What is geophysical survey?

Geophysical survey techniques are used to both discover new archaeological sites as well as to help define and interpret known remains. They surveys build up a picture of the past landscape, detecting archaeological features below ground. The results of a geophysical survey often complement other survey methods, such as aerial photography and fieldwalking.

Magnetometry survey is the most widely used technique as it can cover a lot of ground quickly. This records subtle changes in the local magnetic field; buried features have different magnetic properties to the surrounding soil. Decayed organic matter, as well as burning (such as domestic hearths and bonfires) can transform weakly magnetic oxides into more strongly magnetic oxides.

Some archaeological remains, such as the bases and plinths of kilns that are subject to repeated strong firing during their lifetime, can be very strongly magnetic and are easily detected. The material they produce will also be magnetic to a lesser extent but enough for brick and large accumulations of tile to show up in magnetometry surveys. Ditches and pits can be seen when they have silted up with more magnetic topsoil from adjacent settlement.

This fieldwork is part of the community archaeology project Rendlesham Revealed: Anglo-Saxon Life in South-East Suffolk, funded by the National Lottery Heritage Fund. We are very grateful to our many local and national partners who have made this project possible, and for the support of our volunteers and of the landowners and farmers who work and manage this historic landscape.

If you want to get involved with the Rendlesham Revealed project and future fieldwork, you can sign up to our e-newsletter for updates.