Wednesday, 18 July 2012

Bridging the Gaps: A week of research at Raglan Castle

Recently, I have been involved in a fascinating project at Raglan Castle, home of the Somerset family until 1646, and a key location for the early patronage and protection of the recusant community.

The bowling green and moat walk at Raglan Castle
The project, entitled ‘Bowling Balls or Hidden Halls?’, has been funded by the Bridging the Gaps [BTG] initiative at Swansea University, a collaborative programme that supports projects and activities which foster and develop interdisciplinary research (more information can be found at

Our project, led by Professor Maurice Whitehead, was an interdisciplinary collaboration between the History and Classics Department and the Geography Department at Swansea University to combine historical knowledge with geophysical surveying techniques to learn more about the construction of the castle, particularly during the time of Edward Somerset (1550-1628), fourth earl of Worcester, who was responsible for landscaping the extensive Italian-influenced gardens and developing the moat walk and bowling green.

The team consisted of Professor Maurice Whitehead (History) and Dr Bernd Kulessa (Geography), Hannah Thomas (PhD student in History), Donna Carless (PhD student in Geography) and Dr Adam Booth (Imperial College, London):

Donna Carless                             Maurice Whitehead
Hannah Thomas             Adam Booth

The main aim of the week was to try and establish how the bowling green and terraces had evolved during their construction, and if either had been built over any existing structures that had since remained hidden. Both the bowling green and the terraces have remarkably thin retaining walls that have supported the enormous volume of both structures through nearly four centuries of Welsh rain, without showing the least sign of giving way or leakage, and it is this phenomenon that we hope to gain a better understanding of, using geophysical methods.

We used two non-invasive methods to analyse the bowling green and terraces at Raglan Castle. The first was ground penetrating radar: a sort of X-ray for the ground, which works by transmitting radio waves through the ground to be reflected by hidden features. The reflections highlight contrasts in the soil (for example, a large stone buried in a wet soil will create a contrast) and enable an outline of any buried features to be constructed. The radar is pulled along on a type of sled over a carefully measured out grid, in vertical lines, which can be viewed on the monitor attached to the radar as the data is being gathered. All of the lines will then be placed next to each other during processing and analysis to enable a picture of the whole area to be constructed:

ground penetrating radar 
the radar in action!

The second method that we used was resistivity tomography: a method that sends an electrical current through the ground. The readings are then analysed to establish how conductive or resistive any buried features are, which enables us to establish what they might be constructed of (for example, the conductivity of air vs. that of water is quite different, and allows them to be identified beneath the surface). Similarly to the radar, the data is collected in lines within carefully measured grids, and is processed and analysed to allow a picture of the whole area to be established:

Donna with the resistivity equipment

 Detailed analysis of our findings is currently taking place, and a paper will be presented on the research during Swansea University's Interdisciplinary Research Week in February 2013. The week offered a chance to learn about a whole new discipline, and all members of the team thoroughly enjoyed learning about the 'other', despite the terrible weather and torrential rain that were an unfortunately predominant feature of the whole week! Members of the public and visitors to the castle were also very interested in what we were doing and the methods we were using, and many of them left infected with enthusiasm for uncovering the hidden secrets of Raglan Castle