25. Science-based Conservation andManagement in Wetland Archaeology:The Example of Sutton Commoil, UK Robert Van de lVoort, Henry Chapman and James Cheetham Introduction: Sutton Common Sutton Common comprises the remains of two Iron Age enclosures,which straddle the palaeochannel of the Hampole Beck, which is now completelydrained(Figure 25.1). Both enclosures are situated on "islands" of sands and clay of the 25-foot drift/Lake Humber clays within the Humberhead Levels (Van de Noort & Ellis 1991). This is an extensiveareaof lowlands in eastern England that prior to its drainage in the early seventeenth century was one of the world's greatwetlands. Enclosure A is situated on the east side of the former Hampole Beck, enclosure B on the west side. Enclosure A includes two major phases of occupation - the earlier phase is characterized by a timber palisade demarcatingthe site, the later phaseincludes multivallete ditch and bank arrangements. Evidence for occupation within enclosure B is limited to the later phase only (Parker Pearson & Sydes l99l). The two enclosures are linked by means of a causeway of sands deposited over the peat of the HampoleBeck palaeochannel andflankedby discontinuous post alignments (Van de Noort & Chapman 1999). Both phases remain poorly dated,but both phases of activity on Sutton Common can be dated after 550 cal BC and before 200 cal BC (Parker Pearson & Sydes 1997). Until its enclosure in c. 1850, the area was wet, with peat forming the main soil on the Common, which was predominantlyused as rough pasture. The first drainage ditches were possibly dug as part of the enclosure of the Common, with one ditch clipping the southern tip of enclosure A. Other ditcheson the Common provided more effective run-off of precipitation and soil water. However, the site was more effectively drained in 1983, with the installation of plastic underfield drains placed in coarse gravel ditchesacross the site.Field drainswere not installed within enclosure B, but underfield drains were installed within enclosure A, which had beenbulldozedin 1980. A number of archaeological studies and assessments were undertaken between 1987 and 1993, and suggested that desiccation of organic archaeologicaland palaeo- environmentalremains occurred acrossthe site and with little or no potential for in situ preservation (Adams et al. 1988, Parker Pearson & Merrony 1993, Sydes1992, Sydes and Symonds 1987). The failure to protect the site from drainage and desiccation was discussed on severalocca- sions (e.g.Parker Pearson & Sydes1995). Nevertheless, after lengthy negotiations,the Carstairs Countryside Trust (CCT) bought Sutton Common rn 1997 , with support from EnglishHeritage andthe Heritage Lottery Fund. CCT's primary objective for the future management of the Common was to enable the long-term preservation of the archaeological remains. In 1997, a high-resolution digital terrain model of the Common was createdusing a differential global positioning system(dGPS),which has becomethe basisfor all further research (Chapman& Van de Noort forthcoming). In 1998, EnglishHeritage commis- sionedthe detailed assessment of the hydrology and the preservation of organic remains across the prehistoric site. This studyidentified the existence of extensive waterlogged archaeological remains and the opportunities for their in situ preservation. Background to wetland conservation and management The destruction of wetlandsacross the world, and with it the archaeological sites contained within these wetlands, is well recorded (e.g. Coles and Coles 1996, Bernick 1998). Most wetland archaeological research has beenfocusedon the excavation of sites that were threatened either by the physical destruction of wetlandsor by the indirect effect of the de-watering of areas. In the last threeor four decades of the twentieth century, the need for wetland conservation and management has been highlighted by many national