Jncc coastal Directories Project Region 11 The Western Approaches

1.2.1  Introduction
This section gives a brief introduction to the character of the
region, its wildlife and the extent of its human use and
development, synthesising information presented in
Chapters 2-10.  The main coastal locations are shown on
Map 1.2.1
.  
Map 1.2.2
shows the coastal 10 km squares in the
region.
Region 11 covers the the major part of the coast of
Cornwall, the north coast of Devon, the shores of the Bristol
Channel and the Severn Estuary.  The coast is 1,205.5 km
long (JNCC Coastal Resources Database), which is 6.4% of
the total coastline of Great Britain and includes 18.8% of the
coast of England and 10.8% of that of Wales.  It has a varied
geology but can be characterised in two broad sections - the
cliffed coasts of Cornwall, north Devon and parts of
Somerset, which have a rugged and open character and are
popular tourist destinations, and the low-lying coast of
south Wales and the Severn Estuary, where sedimentary
coastal plain estuarine shores predominate.  
The prevailing wind is from the south-west, and much
of the north coasts of Cornwall and Devon are exposed to its
full force.  The Isles of Scilly, for example, experience 25
days of gales per year.  This compares with the more
sheltered inner Bristol Channel and Severn Estuary, where
figures as low as three days of gales are recorded, at Cardiff
for example.  Owing to the funneling effect of the Bristol
Channel the tidal range of the Severn Estuary is one of the
highest in the world, second only to the Bay of Fundy in
Canada: it reaches as much as 12.3 m at Avonmouth.  This
high tidal range increases the threat of flooding to the low-
lying areas around the Severn Estuary, especially as water
levels may be raised by up to 1.5 m during a storm surge.
Relative regional sea level is rising at an estimated rate of
approximately 2 mm per year, despite the rise in absolute
land level (at a rate of about 0.7 mm per year) as a result of
the removal of the last ice sheets some 10,000 years ago. 
Relatively low-intensity agriculture is a major land use,
with stock farming predominating in the south-west and on
the south coast of Wales.  Around the Severn and the coastal
lowlands of south Wales, crops are grown more intensively,
while the wet grasslands, such as on the Somerset and
Gwent levels, continue to be used for livestock.  These
grasslands are important landscape and conservation
features.  Avonmouth and Cardiff are major industrial
locations built on formerly intertidal land, but over much of
the rest of the region intensive agriculture or industrial
development is the exception rather than the rule.  Fishing
activity centres on the two major ports of Newlyn (one of
the biggest fishing ports in England and Wales) and
Falmouth, both on the south coast, where there are more
diverse fish stocks and numerous sheltered harbours.  The
majority of the coastal area is relatively free from human
infrastructure development, and along much of the coasts of
north Cornwall, north Devon and Somerset, access by road
is not easy.  However, the principal cities of Bristol, Newport
and Cardiff and their associated ports have good road links
with the rest of mainland Britain.  Elsewhere, Newquay in
the extreme south-west, Bude, Weston-super-Mare and, in
Wales, Barry Island are traditional destinations for family
holidays, and the whole of the South-West Peninsula is an
important tourist destination.
1.2.2  Structure and landscape
The solid geology of the region changes from the extreme
south-west to the north and east, at a broad scale being
composed of progressively ‘younger’ rocks.  Most of the
harder rocks of the south-west, including Cornwall, Devon
and the westernmost part of Somerset, are of Carboniferous
or Devonian age (more than 360 million years old).  Land’s
End and the Isles of Scilly are composed of granite, while
the peninsula of the Lizard has an unusual and complex
geology, with ultrabasic igneous rocks that are unique in
southern Britain.  Northwards as far as Minehead the nature
of the predominantly rocky cliffed coast is determined by
the combination of resistant rocks forming headlands or
steep cliffs, within which the softer rocks, typically shales
and slates, erode to form bays or coves.
North and east of Minehead, stretching into Bridgwater
Bay and the Severn Estuary, Triassic (248-213 million years
ago) and Jurassic (213-144 million years ago) rocks are
exposed along the shore.  The relative softness of these
rocks, together with the extreme heights of the tides in the
Bristol Channel, have combined to create a wide rocky
intertidal area along stretches of the coast.  Elsewhere within
the inner Bristol Channel and the Severn Estuary the shore
is defined by tidal flats, which are extensive in places, and
fringing saltmarsh, backed by sea walls.  The sea walls
enclose extensive areas of formerly tidal land, including the
coastal levels around Bridgwater (the Somerset Levels) and
around Cardiff/Newport (the Wentlooge Levels).  
Unlike much of the rest of the UK, the land surface of the
region is thought to have been virtually free from ice for
most of the Pleistocene glacial period, although offshore
there is evidence for the intrusion of a tongue of ice, which
may have extended to the Isles of Scilly. 
1.2.3  The natural environment
The sea and sea bed
The seas in this region are greatly influenced by the Atlantic,
particularly the Gulf Stream, and support important
fisheries.  Mackerel are amongst the most abundant fish
spawning along the edge of the continental shelf to the
south-west.  Herring are locally plentiful, spawning in
Cornish estuaries.  Cod is one of the most important
exploited fish, and there appears to be a pronounced
aggregation of spawning fish off the north Cornish coast
between March and April.  The inshore area has exploited
populations of sea-bed crustacea, notably lobsters.  Offshore
there are extensive scallop and edible crab grounds of
national and international significance.  Basking sharks also
occur in the coastal waters off this region.  
1.2  Introduction to the region
13
1.2 Introduction to the region
Dr J.P. Doody

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