Late Holocene geoarchaeological investigation of the Middle Thames floodplain at Dorney, Buckinghamshire, UK: An evaluation of the Bronze Age, Iron Age, Roman and Saxon landscapes

Large-scale floodplain excavations at Dorney in the Middle Thames valley have revealed organic-rich Holocene palaeochannels as well as a rich archaeological record. High-resolution (decadal) palaeobotanical and sedimentological analyses from a Late Holocene palaeochannel have enabled detailed reconstruction of the landscape spanning from ca. 2850 C14 yr BP (Late Bronze Age), through the Iron Age, Roman and Saxon periods and into the Medieval period (ca. 450 C14 yr BP). The application of sedimentological, palaeovegetation and mineral magnetic analyses coupled with the use of simultaneous R- and Q-mode factor analysis helps to underpin phases of active channel flow, phases of channel ‘ponding’, and alluviation. These phases developed in response to human activity and land use within the region that resulted from deforestation, changes from pastoral to arable practice, burning and the associated destabilisation and inwash of soils into the channel.A series of wooden bridges and timber structures were constructed across this channel between the Middle Bronze Age and Late Iron Age which influenced local sedimentation patterns, fluvial energy and competency within the channel. A number of erosive events coupled with inwashing from the clearance of the last vestiges of woodland for agriculture into an active channel were identified.During the Roman period, flow along the Thames channel ceased, resulting in a pond-like feature in which peaty silts rapidly accumulated. This phase of ponding was punctuated by renewed channel activity in which inorganic carbonate sediments rich in ferrimagnetic minerals were deposited. This coincides with a major peak in cereal cultivation and related catchment disturbance of soils because of ploughing with associated runoff and inwash of soils associated with flooding.