Stanniferous placer development on an evolving landsurface with special reference to placers near St Austell, Cornwall

Abstract

The geomorphic setting of the stanniferous placers of SW England is presented and the history of their development is broadly drawn. In particular, the relationships between the placers and the major types of primary tin deposit in the region are emphasized. The nature and genesis of three placer deposits in the N St Austell district are treated in some detail in order to demonstrate the complexity of placer development in the region as a whole. Stress is placed on an examination of the placer cassiterite morphology to determine the complex genesis of the Cornish deposits. Finally, it is emphasized that the initial stages of placer development in the region are due essentially to processes of disintegration, with processes of decomposition never playing more than a very minor role.