Jncc coastal Directories Project Region 11 The Western Approaches

C.  Contact names and addresses
Type of information
Contact address and telephone no.
Coast protection policy 
*Ministry of Agriculture, Fisheries 
and sediment cells: England
and Food (MAFF), Flood and
Coastal Defence Division, London,
tel: [phone]
Coast protection policy and 
*Welsh Office Environment 
sediment cells: Wales
Division, Cardiff, tel: [phone]
Flood defence - South-west 
*Environment Agency - South 
England
West Region, Exeter, 
tel: [phone]
Flood defence - Somerset 
*Environment Agency - 
and Avon
South West Region, Bridgwater, 
tel: [phone]
Flood defence - Severn 
*Environment Agency - 
Estuary
Severn-Trent Region, Solihull, 
tel: [phone]
Flood defence - Wales
*Environment Agency - Welsh
Region, Cardiff, tel: [phone]
Sediment cells
HR Wallingford Ltd, Howbury
Park, Wallingford, Oxfordshire
OX10 8BA, tel: [phone]
Review of erosion, deposition Minerals Division, Room C15/19, 
and flooding in Great Britain  Department of the Environment, 
(maps and database)
2 Marsham Street, London  
SW1P 3EB, tel: [phone]
North Sea Project data set 
*BODC, Birkenhead, 
CD ROM; tide gauge data
tel: [phone]
*Starred contact addresses are given in full in the Appendix.
2.5  Sea-level rise and flooding
35

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2.6.1  Description
The coasts of this region display a great diversity of
landforms, ranging from the almost continuous cliffs of
Devon and Cornwall to the low-lying muddy coasts of the
Severn Estuary.  Much of the diversity results from
variations in the strength and lithology of the rocks forming
the coast.  
Falmouth Bay - Minehead
Along the coast of Devon and Cornwall, shales and slates
form embayments whilst the more massive igneous rocks
and sandstones form projecting coastal features.  The
tectonic complexity of the coasts of Devon and Cornwall
introduces numerous variations in lithology, resulting in a
diversity in the form of the coast at both local and regional
scales.  The many hanging valleys testify to the erosional
nature of the coast, but the rate of erosion is so slow that an
accurate assessment of the rate of erosion is difficult (see
also 
section 2.4.1
).  
Geological evidence suggests that the high plateau land
surfaces of Devon and Cornwall were incised during
periods of high sea level during the Tertiary.  Lengthy
periods of static sea level produced widespread planation
surfaces, some of which are now backed by ‘fossil’ cliff lines.
Along much of the south Cornish section there are early
Pleistocene cliff and bench features up to 35 m above
Ordnance Datum (OD).  The lowest, at 2-5 m OD, is a raised
beach platform backed by a prominent cliff, the latter
overlain in places by drift deposits, including a periglacial
deposit known as ‘head’, up to 30 m thick.
The Fal Estuary (Carrick Roads) and Helford River are
typical drowned river valleys (‘rias’) and form two of the
few breaks in the cliffed coastline of south Cornwall.  The
cliffs along the eastern coast of the Lizard peninsula are less
steep than those on the western side.  Raised beaches are
found 1-8 m above present beach levels.  In contrast, the
cliffs along the western coast of the Lizard are imposing:
they abruptly truncate the inland plateau surface and are
associated with deep narrow coves and small offshore
islands.  At Church Cove sand blown over the cliff has
partly buried the church tower (Steers 1969).   
Most of the shoreline in Mount’s Bay is rocky, with
narrow, sandy pocket beaches.  However, Loe Bar in the
eastern part of the bay is a shingle and sand bar, kept intact
by the action of waves, which throw material onto its crest.
It confines a freshwater lake which extends 1.8 km up the
valley towards Helston.  The low-lying area of alluvium
between Marazion and Penzance is fronted by sand dunes;
at the entrance to Penzance Dock a submerged forest bed is
exposed at low water.  
Granite forms most of the cliffs from Mount’s Bay to
Cape Cornwall; their character is determined by the
orientation and spacing of joints within the rock.  At Land’s
End the cliffs have a castellated aspect but elsewhere they
are less severe and slope gently towards the sea.  Many of
the small valleys terminate in small bays at the coast, in
many of which remnants of raised beaches are preserved.
The low-lying Isles of Scilly are formed of granite
traversed by mineralised veins and joints.  Marine erosion
has accentuated these planes of weakness to give a
rectilinear aspect to sections of the coast.  Small outcrops of
raised beach and glacial and head deposits are preserved;
these are of great importance in understanding the late
Pleistocene history of southern Britain.  The beaches are
formed of white sand, resulting from marine erosion of the
granite, and carbonate shell sand; locally the sand has been
blown onshore to form dunes. 
From Cape Cornwall to St. Ives Bay the coast is steeply
cliffed.  The lower reaches of the River Hayle, which enters
the sea here, are infilled with alluvium.  The coast to the
north-east of the river mouth is covered with a broad
expanse of sand dunes.  
The coast from the northern end of St. Ives Bay to Cligga
Head is predominantly cliffed, broken only by narrow linear
valleys.  Further north the rocky headlands are interspersed
with sandy beaches.  Holywell and Perran Bays south of
Newquay are backed by an extensive stretch of deep sand
dunes.  Dunes connect Trevose Head to the mainland and
sand dune systems have developed on the sheltered shores
of the Camel Estuary.  Landslips are common along the
coast between Boscastle and Widemouth and produce a
complex, tumbled aspect to the cliffs.  The material forming
the sandy beaches and dunes around Bude is probably
derived from erosion of the exposed cliffs and foreshore.
Northwards towards Hartland Point there are magnificent,
almost unbroken, flat-topped cliffs with a narrow boulder
beach at their foot.  Coastal waterfalls at the seaward end of
hanging valleys are a feature of this coastline and give a
clear indication of the rapid rate of marine erosion,
compared with the slower down-cutting erosion of the
streams.  The steeply-cliffed coast with a wide rocky
foreshore extends along the southern part of Bideford Bay to
the Taw-Torridge Estuary at Westward Ho!.  Many of these
cliffs display long and heavily wooded seaward slopes and
much of the coast is landslipped.
The mouth of the Rivers Taw and Torridge forms a wide
estuary, infilled with Holocene alluvium in its upper part.  A
narrow shingle ridge lies seaward of the dunes at Northam
Burrows, between Westward Ho! and the south side of the
estuary mouth.  Wave action is moving the shingle ridge
landward over the sand dunes.  North of the estuary lie the
extensive dunes of Braunton Burrows, which extend locally
up to 2 km inland and are up to 30 m high.  Wide tidal sand-
flats lie to seaward.   Morte Bay to the north has a fringe of
sand dunes at the foot of steeply rising ground.
The cliffs from Bull Point to Minehead are broken only
by small, narrow valleys with villages such as Coombe
Martin and Lynmouth at their seaward termination.  A mass
of boulders in a delta-like formation occupies the foreshore
at Lynmouth.  The cliffs along this coast are of the ‘hog’s
back’ type, initially cut by marine erosion but having a
series of bevels due to degradation by several stages of
subaerial activity (Arber 1911). 
Porlock Bay west of Minehead is fringed by a shingle
ridge broken only at Porlock Wear, near its western limit.
Littoral drift moves the shingle from west to east along the
Region 11  Chapter 2  Geology and physical environment
36
2.6  Coastal landforms
British Geological Survey

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