Geology - often hidden, but clearly seen from the Coast Path
 See
the Walks
for Everyone pages to find descriptions of Coast Path
walks which are especially good for geology. You can search
for a walk that is known for its geological interest as well
as by area, length and degree of difficulty.
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| Travel
back through millions of years... Look
for evidence of ancient deserts or fossil
forests, track the dinosaurs on the Jurassic
Coast. Follow the path across granite,
serpentine, primeval seabeds and coral
reefs. |
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As you walk the South West Coast Path you will journey across
the varied geology displayed in our coastline.
Some rocks
may not attract your attention while others are more noticeable.
They may be particularly colourful, have unusual patterns,
contain fossils or be contorted into fantastic shapes.
These features are all evidence of how and where rocks were
formed. As they vary in age, they provide a record of how
the environment has changed over hundreds of millions of
years.
The coastal geology of Dorset and East Devon is so unique
and played such an important part in the development of the
earth sciences that it has been designated a World Heritage
Site.
Here’s a whistle-stop tour of some geological stories
you will encounter along the South West Coast Path.
Links on this page:
Exmoor, North and South Devon and Cornwall - Shales, Slates
and Sandstones
These rocks were laid down over several
hundred million years when this area was part of a vast ocean
basin. Sediments that were eroded from the adjacent land
were deposited in the sea by rivers. Coarse sediments were
laid down in deltas and shallows to eventually form sandstones,
while fine particles were carried into deeper water to form
mudstones and shales. Fossils of animals and plants characteristic
of these different environments are found locally. These rocks were later affected by intense heat and pressure,
changing their character and distorting them into faults
and folds. The Coast Path walker will see especially spectacular
examples of folded rocks on the north coast between Hartland
and Crackington Haven.
Pentire Head, North
Cornwall – a
submarine volcano
Roughly 370 million years ago the area
that is now Devon and Cornwall lay under
shallow seas. In places, submarine volcanoes
were erupting. On the Coast Path the results
are dramatically displayed at Pentire Head
east of the Camel estuary. The rocks here
show their origins in two ways. Between
Pentire Point and the Rumps you can see
what looks like a pile of rock pillows
which formed as the lava skinned over as
it cooled in contact with the sea. Petrified
gas bubbles were trapped inside and these
can be seen in some individual rock outcrops.
Cornwall - Minerals and Mining
Ruined engine houses are a
common sight on the Coast Path in West Cornwall, memorials
to a mining industry that flourished from the Bronze Age
until comparatively recently.
Six areas adjacent to the Coast Path are now part of the Cornish Mining World Heritage Site – the St Agnes Mining District, Portreath Harbour, the ports of Hayle and Charlestown, the St Just Mining District and Trewavas. To find out more, visit: www.cornish-mining.org.uk, http://whc.unesco.org/
The presence of tin, copper and several other minerals is
related to the granite masses of South West England. As magma
cooled to form granite, hot gases and super-heated water
penetrated cracks and fissures in the surrounding rocks.
The water and gases cooled and the chemical elements they
contained crystallised out as mineral veins. High temperature
minerals (such as tin and copper) were deposited closest
to the granite, and lower temperature ones (such as zinc
and lead) further away.
The Lizard - Serpentine and other curiosities
South of a
fault line between Polurrian Cove and Porthallow the Coast
Path walker is walking on rocks that came from several
miles below the surface of the earth some 375 million years
ago. It is thought that the rocks here formed deep in the
Earth’s
crust and were pushed up to form the unusual rocks of the
Lizard Complex. Basalt, gabbro, gneiss, schist and serpentine
are some of the rocks you will encounter.
You will come across all of these as you walk the Coast
Path around the edge of the Lizard. The serpentine varies
from reds to greens and greys - colours that are beautifully
brought out when the rocks are wet or polished. Look out
for sea-washed beach pebbles and the serpentine souvenirs
made and sold locally to see this effect. You will also find
it where thousands of feet have polished the serpentine stones
in the surface of the Coast Path and its stone stiles.
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