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Conservation of the Cave
The following links to a BBC Look East feature about conservation issues in the Cave.
BBC Look East
The following article appears in issue 1 2010 of Cornerstone magazine, the magazine of the Society for the Preservation of
Ancient Buildings. In this article, Tobit Curteis, the Cave�s conservator explains some of the challenges facing us today:
Tobit Curteis, wall paintings conservator and specialist in
environmental control at historic sites, outlines his recent work at
Royston Cave
Royston Cave is a remarkably unusual survival, and all
the more so due to that it is almost unknown outside the local area.
The Cave is carved into a bed of soft chalk less than a metre under the
street. Although the Cave originally predates the medieval period, it
appears that it was enlarged and carved with both Christian and
mystical symbols between the 14th and 16th centuries.
At some point the Cave was partially filled in and forgotten, and it
was not until the middle of the 18th century that it was rediscovered.
No record of the Cave before the 18th century is known, but since this
time there has been continual deterioration of the carved detail. Over
the course of the past 50 years numerous attempts have been made to
understand the deterioration and to repair the damaged carvings.
However, most studies have ended prematurely and only limited remedial
measures have been implemented. In 2008, a detailed study of the Cave
was commissioned by the Royston Town Council and supported by a
generous grant and specialist advice from English Heritage, with the
aim of understanding how and why the Cave is deteriorating, so that
measures to conserve it could be developed.
It immediately became apparent that the causes of deterioration are as
unusual as the Cave itself. Because it is carved in soft, Upper
Cretaceous chalk, (rather than the harder, older beds) very little
research has been done on the precise decay mechanisms or their
control. To add to this, there is relatively little research in the UK
on the deterioration of this type of cave structure. Therefore, the
project, which will take a number of years to complete, involves basic
materials research, as well as the latest digital survey techniques
more commonly associated with historic building conservation.
The preliminary results have demonstrated that the primary cause of
deterioration appears to be minor dimensional change of the chalk, as a
result of fluctuations in the moisture content, resulting largely from
periodic flooding, but also due to changes in the microclimate. This
leads to internal stresses which cause fine cracks to occur, often in
the vertical plane between the raised carved detail and the main face
of the Cave. The fissures are then colonised by microbiological growth
and animals, causing the cracks to enlarge and eventually these
sections of carving to fall away. Historically, this may have been
exacerbated by traffic vibration, although since the opening of the
nearby bypass in the 1980s, this is likely to have been substantially
reduced.
In conjunction, damage has been caused to the chalk by worms, which
appear to feed on nutrients which have entered as a result of flooding
with fowl water. The effect of the worm activity is to cause a loss of
cohesion and collapse of certain sections of a softer chalk and a
consequent loss of the carved detail.
With the basic decay mechanisms now apparent, both preventive and
interventitive conservation approaches are being evaluated. As with all
sensitive historic structures, the primary aim is to control the
deterioration mechanisms and, therefore, minimise the level of
treatment that needs to be applied. Given the unusual nature of the
structure and the limited reversibility of treatments, an extremely
cautious approach is being adopted, and the conservation process will
be slow and painstaking. Indeed, the real conservation process will be
open ended as, once the current phase of damage is stabilised, the long
term survival of the Cave depends on preventing future deterioration,
rather than treating it once it has occurred.
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ROYSTON CAVE