The town's setting is dominated hy the granite heights of Carn Brea and Carn Marth.
Granite is an igneous rock formed from molten material generated at great depth below the surface.
Vapours from the granite carried minerals into the rock's fissures before it finally set. In later ages the granite was lifted by earth movements, and exposed to weathering. On Carn Brea can he seen the remains of one of the oldest and largest human settlements in Cornwall, a 46-acre Neolithic hillfort. Minerals were probably worked here since the Bronze Age, and by the Middle Ages mining was well estahlished. Tin was obtained from deposits in the flats of streams the ore faund in material produced by the weakening of veins in the granite.