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This paper will describe two phases of investigation to characterize conditions that have led to preservation of archaeological remains beneath the historic core of Nantwich. It will discuss the different types of monitoring employed and the relative merits between methodologies for monitoring key indicators, and outline experimental methods for the application of gas monitoring. The Nantwich project is in the middle of a five year programme and therefore interpretations presented here are provisional, and are briefly compared to similar studies from York. The continuation of conditions that have preserved organic remains beneath these two historic centres for over a thousand years are now subject to threat due to various causes from the impact of the modern world, and the conclusions suggest that achieving long-term sustainability of preservation conditions will require a holistic approach from spatial planners, engineers, hydrologists and archaeologists. [ABSTRACT FROM AUTHOR]

This paper discusses the approaches to characterizing and monitoring two very similar sites in proximity. It explores the paucity of scientific evidence for understanding conditions of preservation, and techniques for monitoring it, that presently exist for sites that lie in superficial unconsolidated sediments within which a capillary fringe has developed above a groundwater table, rather than for a more conventional water-logged site. Challenge and review by peers is essential for a robust approach to ensuring management measures are appropriate, rather than relying on the knowledge and experience of a single individual or team. Since 2007, a monitoring programme for the internationally important timber platform at Hanson's Must Farm clay extraction site has been developed and enhanced, whilst excavations within the footprint of the quarry have revealed outstanding preservation of organic remains. The 3000 year inundation and sedimentary sequence, and the 100 years recent development in this landscape, are described along with the unusual preservation processes which have contributed to exceptional survival of archaeological remains. The results from Must Farm are contrasted to the paucity of monitoring data from Flag Fen, and the separate trajectories between a developer-funded project and a nationally protected monument are discussed. [ABSTRACT FROM AUTHOR]

Abstract: Environmental change caused by urban development, land drainage, agriculture or climate change may result in accelerated decay of in situ archaeological remains. This paper reviews research into impacts of environmental change on hydrological processes of relevance to preservation of archaeological remains in situ. It compares work at rural sites with more complex urban environments. The research demonstrates that both the quantity and quality of data on preservation status, and hydrological and chemical parameters collected during routine archaeological surveys need to be improved. The work also demonstrates the necessity for any archaeological site to be placed within its topographic and geological context. In order to understand preservation potential fully, it is necessary to move away from studying the archaeological site as an isolated unit, since factors some distance away from the site of interest can be important for determining preservation. The paper reviews what is known about the hydrological factors of importance to archaeological preservation and recommends research that needs to be conducted so that archaeological risk can be more adequately predicted and mitigated. Any activity that changes either source pathways or the dominant water input may have an impact not just because of changes to the water balance or the water table, but because of changes to water chemistry. Therefore, efforts to manage threatened waterlogged environments must consider the chemical nature of the water input into the system. Clearer methods of assessing the degree to which buried archaeological sites can withstand changing hydrological conditions are needed, in addition to research which helps us understand what triggers decay and what controls thresholds of response for different sediments and types of artefact. [Copyright &y& Elsevier]