Plynlimon research catchments: soil parent materials

Distribution of soil parent materials in the Severn and Wye catchments. These were mapped during the Soil Hydrology Study conducted by JP Bell in 1968-1969: Bell, J.P. (1969). The Soil Hydrology of the Plynlimon Catchments. Institute of Hydrology Report No. 8, Institute of Hydrology, Wallingford, UK.