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.
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| 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 www.swansea.ac.uk/btg)
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):
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| Donna Carless Maurice Whitehead |
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| 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:
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| ground penetrating radar |
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| 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:
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| Donna with the resistivity equipment |
