The Geology of Cornwall

Cornwall can really be imagined as a finger of 400 million year old Devonian slates along with Carboniferous sandstones and shales pointing across the Atlantic Ocean towards the USA, with a backbone of granite. The granite batholith forms moors at Bodmin Moor in the east and reappears in the granite outcrops near Roche in Mid Cornwall and in West Cornwall at the Carnmenellis Granite (dated at about 270 million years old). The latter now largely covered by human habitation, south of Camborne-Redruth and in the far west at the striking and rugged landscape of the Penwith Granite. It is also present, but less apparent, due to its highly weathered or kaolinised state in the St. Austell Area where it appears as 'china clay'. Two excellent guidebooks are the heavyweight Geology of Cornwall by Selwood, Bristow and Durrance and the 'cheap as chips' West Cornwall: A Landscape for Leisure (Holiday Geology Guidebook) by A.J. Goode and M Leveridge Holder.

Two very significant areas for both the amateur and keen geologist must surely be the tlted rock strata of the north cornish cliffs between Millook Haven and Woolacombe in Devon - see Earth movements and folding on a grand scale... The other has to be the metamorphic thrust zone of the Lizard Peninsula. An area of varied geology and landscape has essentially been formed by the collision of two tectonic plates.

Examine a Map of the Lizard Peninsula. The Geology can be examined in more detail here