Monuments at Risk in England's Wetlands (MAREW)

The final building block in developing our wetland strategy was the Monuments at Risk in England's Wetlands Project, which was commissioned from Exeter University in 2000 (www.ex.ac.uk/marew). This desktop assessment collated data on the destruction of wetlands in England over the past 50 years together with evidence for the rate of destruction or damage to archaeological sites in wetlands. It provides a general picture of the condition of England's wetland archaeological resource and the risks it faces, and creates a benchmark against which future changes can be monitored. It examined, in particular, the effect of hydrological changes on waterlogged organic archaeological and palaeoenvironmental remains, and also looked at the impact on the archaeology of wetlands of peat extraction, forestry, and urban and industrial expansion. The project collated and assessed information on governmental and non-governmental policies that effect wetlands and wetland archaeology.

Drawing on the results of the existing surveys, together with data drawn from relevant Sites and Monuments Records, it is now possible to calculate that the average density of archaeological sites in all England's wetlands (including lowland and upland peatlands, and alluviated lowlands) is 1 per 100 hectares (220 acres), with an estimated total of at least 13,400 individual monuments. Before the drainage and cutting of peat, each of these sites would have been well preserved, and many would have contained important waterlogged materials.

 The most visible and widely recognised threat to the wetland archaeological resource is peat extraction, and several organisations including the Council for British Archaeology have long campaigned against the continued extraction of peat. However, the project demonstrates clearly that the greatest impact is from the drainage of land for agriculture and the subsequent drying out of the archaeological remains, followed by peat wastage from agricultural land. Other significant threats include urban and industrial expansion onto wetlands and the eutrofication of peat through agricultural fertilisation. In all, an estimated 1.1 million hectares of wetlands can now be shown to have been destroyed as a result of these various threats. New threats, such as short rotation cropping (including the encouragement of energy crops as part of the England Rural Development Programme) continue to emerge. Generally the lowland wetlands have suffered considerably more that the upland wetlands, many of which are located in our national parks (eg Dartmoor, Exmoor, the Peak District) and are subject to a rather more sympathetic land management regime. Nevertheless, taken across the country as a whole, the rate of destruction of the wetland archaeological resource over the past 50 years is staggering. The great majority of the estimated 17,780 potential sites will have been destroyed or damaged, resulting in the unrecorded loss of a very significant part of our cultural heritage. Only an estimated 4,380 sites are likely to survive more or less intact buried beneath upland and lowland peats.

Of the surviving wetlands less than 1% constitute areas of semi-natural land, or are under active nature conservation management (although much larger areas are subject to schemes that benefit from land management and conservation regulations and subsidies that recognise and enhance wetland habitats). In most cases such measures help protect the archaeological resource by discouraging the conversion of pasture into arable land. Nevertheless, the use of fertilisers on permanent pasture and the variable watertable that exists in such schemes (high in the winter but lower in the summer), continue to pose a serious threat to the waterlogged archaeological resource. Despite the conclusions of the Wetland Management Project, close co-operation between nature conservation agencies and the archaeological community has been slow to develop.

The project also surveyed the prevailing land use and management regimes of surviving wetland areas in order to estimate the current condition of our wetland heritage. Although the majority of known wetland monuments have increasingly suffered from partial destruction and desiccation and a very significant number have been completely destroyed in the past 50 years, the extent of unsurveyed wetland areas (including the intertidal wetlands and urban waterlogged deposits) is still considerable. The archaeological potential of these areas has now been shown to be very high and it is essential that we develop effective mitigation strategies as soon as possible if we are to avoid the large-scale destruction typical of previous decades. Hydrology is the critical factor in the preservation of the archaeology of England's wetlands, and archaeological wetland sites can only be preserved if their hydrology can be controlled. The project highlighted first the fundamental need for better prospection techniques to identify wetland archaeology and then for new approaches to the management and conservation of wetland deposits. These must address issues of drainage, catchment, and water quality, and have the objective of preserving whole wetlands rather than isolated sites or 'islands' of monuments. This broader approach requires a very real and active partnership between the archaeological community and the nature conservation world, and the co-operation of a wide range of interest groups, all of whom need to act in concert to preserve the natural, cultural, and recreational values of our surviving wetlands.