Anthropogenic alluvium: An evidence-based meta-analysis for the UK Holocene

An exploratory meta-analysis of 14C-dated Holocene anthropogenic alluvium (AA) in the UK is presented. AA units were categorized by grain size, catchment area and location, depositional environment, and according to diagnostic criteria linked to recorded types of anthropogenic activity. The oldest AA units date to the Early Bronze Age (c. 4400 cal. BP) and there is an apparent 1500 year lag between the adoption of agriculture (c. 6000 cal. BP) in the UK and any impact on floodplain sedimentation. The earliest influence of farming on UK rivers appears to have been hydrological rather than sedimentological. The mediaeval period was characterized by accelerated sedimentation of fine-grained AA, notably in the smallest catchments. There are some apparent regional differences in the timing of AA formation with earlier prehistoric dates in central and southern parts of the UK.