The geology of Cornwall provides a wealth of variation from the oldest
rocks of the Lizard peninsula which could date from as far back as the
Pre-Cambrian period over 600 million years ago to Cornwall's most recent
geology of the Late Tertiary and Quaternary periods up to 70 million years
ago.
Much of Cornwall's geology belongs to two well known periods: Devonian,
the rocks being described locally as 'killas' and over 400 million years
old; and from the Carboniferous period 350 million years ago.
Even the oldest rocks of the Lizard have undergone metamorphic transition
over their lifetime, with the intrusion of igneous rocks. The famous
serpentine stone in its green and red varieties has found its way across
the world, taken as a lighthouse or ornament, a momento or souvenir from a
visit to the Lizard peninsula.
Cornwall's scenery is characterised by its geology, particularly its
granite, which shapes its uplands and moors. The Land's End peninsula
consists entirely of granite which gives it its unique appeal, rocky
cliffs carved into pillars and blocks by time, inland moors with carns and
craggy peaks and one of Cornwall's most popular rock climbing areas,
Bosigran.
Extending along the central spine of Cornwall these granite bosses extend
from the Land's End to Tregonning, Carnmenellis, Redruth and Carn Brea,
Helman Tor and the Luxulyan area of Central Cornwall to Bodmin Moor in the
north with another small granite intrusion in south east Cornwall at
Gunnislake and Kit Hill.
Some fossils can be found in Cornwall in the metamorphic and sedimentary
rocks from the Devonian and Carboniferous seas. Bude, Padstow, Trevose
Head and Trevone are some of the best areas of North Cornwall for
discovering fossils including brachiopods, sea lilies and bryozoa.
The north coast of Cornwall provides many fascinating geological sites
including: the visually stunning Millook Haven with its sandstones and
shales folded in an amazing zig-zag formation; Lanterdan Quarry near
Trebarwith with its towering slate pillars; the raised beach at Porth
Nanven on the Land's End peninsula; St Agnes Beacon, once an island;
Cligga Head, near Perranporth, a granite outcrop with exposed greisen
veins; and the Rocky Valley, a gorge near Tintagel.
Cornwall's south coast offers more geological sites, different in nature
but equally spectacular including: the stretch of coastline from Land's
End to Gwennap Head with its amazing granite formations; the Logan Rock,
near Treen, a 65 tonne granite boulder which 'logged' or rocked when
pushed by the hand of a single person; the Loe Bar, near Helston; the
Devil's Frying Pan near Cadgwith; the Fal estuary, a ria and one of the
largest natural harbours in the world; and the raised beach at Carne on
Gerrans Bay.
Central Cornwall boasts one of the strangest sites, Roche Rock, an outcrop
of rock rising from an otherwise normal area crowned by the ruins of a
15th century chapel. The view is quite unexpected and is well worth a
visit. Bodmin Moor offers some fascinating sites of the so called 'Cheesewrings'.
The best is on Stowe's Hill, a short walk from the village of Minions on
the east of Bodmin Moor.
Cornwall's wealth of geology resulted in a rich mineralogical history,
which was the mainstay of Cornwall's industry for several centuries. The
picturesque stone engine houses and chimneys which are scattered across
Cornwall's landscape are a reminder of this industrial activity and are
now recognised as a World Heritage Site of international importance.
Today, these stone monuments to a bygone age are appreciated by visitors
and residents alike, who study and preserve them and the minerals and
techniques associated with this industry.
Mineralogists will find a fine collection of Cornish minerals extracted
from mines around Cornwall housed in the Royal Institution of
Cornwall Museum in Truro, including: cassiterite (tin oxide); chalcopyrite
(copper and iron sulphide); chalcocite (copper sulphide); galena (lead
sulphide); native copper (pure copper metal in flattened leaflike sheets);
cuprite (red copper oxide); haematite (iron oxide); zinc blende (zinc
sulphide); wolframite; iron pyrite; siderite (iron carbonate); malachite;
bournonite; and cerussite (lead carbonate).
The economy of Cornwall depended for many years on the mining of tin,
copper, lead, zinc, manganese, iron, wolfram, silver, antimony and
uranium.
Central Cornwall, around the St Austell area, is still famous for the
production of kaolin or china clay used in the ceramic industry and in
paper. Huge open cast pits can be seen, some of which have now been
reclaimed and the snow white towering pyramids of this area are known by
locals as the 'Cornish Alps'.
Mining in Cornwall and the sites associated with it have been recognised as internationally important and awarded the status of being a World Heritage Site. The World Heritage Site encompasses mining landscapes dating from 1700 to 1914, when deep hard-rock mining was developed in Cornwall and when major developments in technology within Cornwall helped to transform mining both locally and worldwide.
The ten areas which are included in the World Heritage Site, chosen for where the physical remains of mining from this period are best represented include: St Just in Penwith; Hayle; St Day/Gwennap; Camborne/Redruth; Godolphin/Tregonning; Wendron; St Agnes; Caradon; Luxulyan Valley and Charlestown; Tamar Valley and Tavistock.
Other economic geology still being carried on in Cornwall is the quarrying
of certain types of stone. In Delabole, in North Cornwall, slate is
quarried from a huge open pit just outside the village. The quarry is a
fantastic sight at over 500 ft deep and has been in production since the
1200s.
For more information about individual sites, visit our A-Z of Cornwall, where you will find information in our
index of town and individual site pages.
Use the + scale on the left of the map to zoom in on an area. Click on a marker to see the name of the location and click the box to go to the information about that place. To zoom out click - on the scale. (Google Map integrated by www.choughmountain.eu)
