sentences:  In places these have been subjected to severe folding, as can be seen on the north coast near Crackington Haven, spectacularly at the "Whaleback Pericline" on the beach just south of Bude and at several other locations.The intrusion of the granite into the surrounding sedimentary rocks gave rise to extensive metamorphism and mineralisation, and this led to Cornwall being one of the most important mining areas in Europe until the early 20th century.It is thought that tin ore (cassiterite) was exploited in Cornwall as early as the Bronze Age.