The central aim of the project is to examine and quantify the physical and chemical impact of bracken rhizomes on sensitive archaeological deposits in a granite upland context. Much of Dartmoor's rich archaeological landscape is often perceived as being generally stable, with only occasional damage as a result of visitor or agricultural pressures. The picture is however, probably much more complex, and in particular, work carried out by botanists indicates that bracken in particular is causing both physical and chemical damage to the areas which it colonises. The impact of the plant on underlying geology and geomorphology is now being appreciated thanks to the work of Professor Roy Brown and others, whilst in Scotland, work at Lairg has indicated the often considerable physical impact of the rhizomes on archaeological deposits. On Dartmoor and other parts of the country, work has been carried out in trying to control the spread of the plant, but such exercises are very expensive. Bracken establishes itself on relatively well drained ground and on Dartmoor this often coincides with archaeological remains, which as a result, means that large numbers are seasonally obscured, and the clearance of the plant could be justified on aesthetic grounds alone. The potential problem is however possibly much greater than the inconvenience of being denied access and past work has suggested that the archaeological information held within each site maybe being severely compromised or even destroyed. Given the nature of this threat to such an important archaeological resource it is clearly of paramount importance that the scale of the problem be assessed and quantified. The central aim of the Dartmoor Archaeology and Bracken Project is to accurately quantify the scale of the problem and establish the precise nature of the impact on archaeological remains.
The project is expected to make a significant contribution to our understanding of the impact of bracken on sensitive archaeological deposits in an upland granite environment. It is generally accepted that bracken is causing damage to archaeological deposits, but to date the precise mechanisms by which this is occurring have not been examined. This project sets out to quantify this damage using the sensitive archaeological deposits known to exist within the interior of prehistoric buildings. Using the results from this exercise it is anticipated that more fully informed decisions concerning the management of bracken on all archaeological sites will be possible. The impact of this research could therefore be seen as having widespread implications for the more successful management of upland bracken infested sites. A secondary result of the work will be an opportunity to enhance our understanding of the Kestor parallel reave system, which was the first one on the moor to be examined under “modern” excavation conditions. Details of house structure and layout will be recovered together with dating and environmental information. Artefacts may be encountered which will provide a valuable insight into the economy and use of the building.
This project is being set up primarily to look at one and until now totally neglected aspect of Dartmoor's archaeology. Namely, to examine the precise character of the impact of the bracken which is rapidly infesting areas of outstanding archaeological national importance. Round houses have been selected for study, for a number of reasons. First, they are relatively common on the moor, with over 5000 examples currently recorded. Second, previous work has indicated that the stratigraphy within many buildings is relatively complex and therefore susceptible to bracken damage. Third, excavations have shown that the depth of deposits within many houses are relatively shallow and certainly within the reach of bracken rhizomes. Fourth, the closed nature of deposits within houses will allow careful analysis of the phenomena in a well defined and relatively small area. All other types of archaeological site do not meet all of these criteria. Having established that round houses are the most suitable form of surviving archaeological remain to examine, the next stage was to select an example which meets a certain number of important criteria. The choice of potential sites on Dartmoor is immense with over 5,000 examples currently known. Around 70% of these structures are presently protected as Scheduled Ancient Monuments and about 40% are known to be infested with bracken to some extent. Therefore, the choice of sites is limited to around 2,200 houses, some of which have been excavated in the past. It is crucial to the success of the excavation that once the site is being investigated that a strict control on access to it by people and animals is possible. On the open moorland such controls would be very difficult and therefore it is essential that the site lies within enclosed land where access by both people and animals can be restricted. Most known bracken infested sites lie on open access Commons and therefore, do not meet this criteria. Estimates of how many sites are both bracken infested and on private land with no public access are difficult to access, but based on personal examination of over 3000 houses, the figure will be no greater than 100. Bracken is known to be the source of a number of health risks and therefore ideally a site which itself is bracken infested, but which lies within an area with no other bracken would be ideal on health and safety grounds. Clearly logistical factors need to be taken into account and amongst these are ease of access to the site. Finally a supportive owner is crucial to the success of the project. The only house which was currently known to meet all of these criteria lies at Kestor on the edge of a well preserved and contemporary Bronze Age coaxial field system.
