Metalliferous Mine Waste in West Cornwall: The Implications for Coastal Management

Abstract

Metalliferous mining has taken place in Cornwall since the Bronze Age. Copper production in southwest England peaked at 15,255 tonnes of metal in 1860, while c. 12,794 tonnes of tin metal represented its peak production in 1870. Technologies of varied efficiency were employed in the mining industry, which produced large quantities of unwanted material. Waste was frequently disposed of by flushing sediments into localwater courses. Much of this material was subsequently transported to the coastal zone. Coastal and river floodplain stratigraphi es indicate the presence of mine waste deposits. These are visually distinctive , consisting of finely laminated minerogenic-dominated strata which frequently exhibit a red-brown or grey-green coloration. The structure and text ure of these materials corresponds closely with documentary descriptions of mine 'tailings' or 'slimes'. Geochemical analysis of sedimentary cores from selected sites shows that coastal sediment sequences display concentrations of heavy metals in excess of that which may be expected from normal precipitation and weathering. It is concluded that any future large scale disturbanc e of these deposits may have a significant environmental impact due to heavy metal contamination of sediments, water and biota. A co-ordinated coastal management strategy may help minimise degradation of the coastal resource.