The River Axe is a groundwater-fed stream whose catchment has experienced metal mining in the past. Its channel activity rates are low and recent alluviation appears to have occurred by overbank deposition of fine-grained sediment. The influence of mining on flood-plain sedimentation over a period of nearly 300 years is examined through the analysis of sediment heavy metal chemistry. The most recent phase of mining (1858-1908) is particularly well-documented and provides an excellent opportunity to first, assess the impact of a dated pulse of 'labelled' sediment on flood-plain deposition, and secondly, to evaluate the use of heavy metal chemistry for indirectly dating alluvial sediments. 'Dating' of fine flood-plain sediments by means of their contained heavy metals permits not only the elucidation of the sequence and pattern of valley alluviation, but also 'quantitative' estimates of rates of flood-plain sedimentation for the last 300 years. Metal mining accelerated fine sediment yields with flood-plain sedimentation rates ranging from 8-8-16.0 mm a-1 when the Priddy minery was in operation, compared to 2-4-4.6 mm a1 when mining activity ceased.