Cornubian batholith

Map showing the main granite outcrops of the Cornubian batholith in southwest England and the location of another granite outcrop called the Haig Fras. The dotted line shows the area of negative gravity anomalies associated with these batholiths due to their relatively low density compared to average continental crust. The lines represents the 20 mGal Bouguer anomaly.

The Cornubian batholith is a large mass of granite rock, formed about 280 million years ago, which lies beneath much of Cornwall and Devon in the south-western peninsula of Great Britain. The main exposed masses of granite are seen at Dartmoor, Bodmin Moor, St Austell, Carnmenellis, Land's End and the Isles of Scilly. The intrusion is associated with significant quantities of minerals particularly cassiterite, an ore of tin which has been mined since about 2000 BC. Other minerals include china clay and ores of copper, lead, zinc and tungsten.

It takes its name from Cornubia, the Medieval Latin name for Cornwall.