A line of time: approaches to archaeology in the Upper and Middle Thames Valley, England

Since the 1970s large-scale archaeological projects have been undertaken in the Upper and Middle Thames Valley, driven by development pressures and strongly influenced by the evidence of aerial photographs, most of which have been of the higher gravel terraces where cropmarks are most prolific. These sites have, however, usually suffered heavily from ploughing; water-logged deposits, occupation horizons and buried soils are rare. In contrast, the preservation of archaeological and environmental deposits are of much better quality on the valley floor, although the sites are generally difficult to locate, being buried beneath alluvium deposited during the past 1-3,000 years. Pressure on gravel deposits means that mineral quarries are increasingly moving onto the lower ground. However, changes in planning policy in the UK now promote the archaeological evaluation of these areas as a result of which buried prehistoric. Roman and medieval landscapes, including new types of well-preserved site and activity areas, are being located close to the Thames, particularly at Yarnton, Oxon, and on the site of the Eton College Rowing Lake, Bucks, where ancient landscapes are more complex and reflect a wider variety of human activities than those revealed previously by past, economically focused research.