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This page was updated on 1st May 2007.

The geology of Devon is unique in Great Britain. The County is the only one that has given its name to a geological system, the Devonian System, that is used world-wide for all rocks of this age.

Devon also contains rocks of the Carboniferous System which take their name from the coal which they contain elsewhere in Britain.

Some 300 million years ago the Devonian and Carboniferous rocks were part of a, now vanished, chain of mountains. The intense crumpling to which these rocks were subjected is beautifully displayed in the cliffs from Bude to Hartland Point (North West Devon) and can be seen in many inland County Geological Sites and on the coast from Torbay to Plymouth (South Devon).

The Granite of Dartmoor moved up into the folded rocks during the formation of the mountains. The fluids circulated by heat from the granite caused the formation of the minerals which were the source of the once important mining industry, and the present china clay deposits of Devon.

The famous red soils of the County lie on red coloured Permian and Triassic rock that formed when the ancient mountains and the top of the granite were worn away in a desert climate. They are well displayed along parts of the south coast of the County.

In East Devon Jurassic rocks laid down in seas during the age of the dinosaurs have yielded important fossils of these creatures. The seas that deposited the white chalk once covered the whole of Devon. Chalk now only occurs in parts of East Devon, but flint gravels derived from chalk are scattered more widely across the County.

Some of the youngest geological features are the important Tertiary ball clay deposits of Bovey Tracey and Petrockstow - two of the three places in the UK where such clays are worked. Because the ice sheets of the Pleistocene only touched the north coast of Devon, many interesting Tertiary and periglacial features are preserved in the Devonshire landscape.

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