Jncc coastal Directories Project Region 11 The Western Approaches

ridge, and the pebbles increase in roundness eastwards.  
At present natural and man-made changes threaten to
breach the ridge near its centre.  The large tidal range and
high wave energy in the bay has resulted in the exceptional
height of the eastern part of the ridge.
Minehead - the Severn
At Minehead a large area of intertidal mud and shingle
stretches for almost 9 km along the shore.  Eastwards, the
form of the coast changes abruptly to low, steep cliffs,
fronted by a wide foreshore covered with sand, shingle,
mud or bedrock platform.  Landslips are common where the
red marls of the Mercia Mudstone Group form cliffs.
Groynes are common along stretches of this coast and their
infill shows that littoral drift of the shingle is consistently
eastward.  The occurrence of damaged groynes within some
lower shingle beaches indicates that coastal erosion is
locally a major problem. 
The coast fringing Bridgwater Bay, from Hinkley Point
north-eastwards to Brean Down, marks the seaward limit of
the low-lying Somerset Levels, an area of Holocene
sediments up to 25 m  thick.  The intertidal flats along the
shore here are up to 6 km wide at low spring tides.  Along
the south coast of the bay the flats are covered with mud
and bordered by a narrow but continuous shingle ridge
which terminates at Stert Point near the mouth of the River
Parrett.  Along the eastern coast of the bay the mud flats
(Berrow Flats) pass landward into a flat sandy upper beach.
Sand dune systems have developed along the coast of the
three westward-facing bays from the mouth of the Parrett
northward to Middle Hope.  Saltmarsh development along
some of this coast indicates coastal accretion, but much of
the dune system is retreating.  In Sand Bay beach
replenishment has been used to protect the man-made sea
walls in front of the dunes.
The southern coast of the Severn Estuary, from Middle
Hope to Clevedon and from Portishead to north of
Avonmouth, is formed of low, predominantly muddy
Holocene estuarine deposits, protected by a low sea wall.
Along the upland area from Clevedon to Portishead the
wooded interior slopes gently down to the steep, rocky
foreshore.  
The estuary has one of the highest tidal ranges in the
world (see also 
section 2.3.4
), resulting in a wide intertidal
zone.  
2.6  Coastal landforms
37
Predominantly cliffed coast
Sand dunes
Shingle storm beach
Low-lying alluvium
Landslip
Soft estuarine shore
Land’s
End
Lizard
Point
Church Cove
Isles of
Scilly
Westward Ho!
Camel Estuary
St Ives Bay
Lundy
Minehead
Nash Point
Bridgwater
Bay
Porthkerry
Severn
Estuary
Bristol
Channel
Celtic
Sea
Regi
on
10
Region 12
5°W
Map 2.6.1
Major coastal landforms

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The Severn - Kenfig
Muddy Holocene sediments mark the coast along the
northern shore of the Severn Estuary as far west as Cardiff,
with a sea wall protecting the low ground of the Caldicot
and Wentlooge Levels, which are separated by the estuary
of the River Usk.  Areas of saltmarsh front the sea walls.
These shores have a long history of accretion and erosion,
documented by changes in the level of the saltmarsh and the
dates of artifacts found associated with each level (Allen &
Rea 1987).  Erosion continues in places on the foreshore but
is limited by the sea walls.  Peat deposits, which locally
contain tree-trunks, are exposed on the foreshore above the
early Holocene muds. 
South and west of Cardiff the coastline is mostly cliffed
as far as Ogmore-by-Sea.  Typically, steep cliffs are fronted
by a wide rock-cut platform.  There are minor pocket
beaches, for example at Whitmore Bay on Barry Island, and
a fine shingle storm beach fronts the cliffs at Porthkerry.
The cliffs are broken by the valley of the River Thaw at
Aberthaw, where a highly dynamic shingle spit dominates
the shore.  Between Aberthaw and Ogmore-by-Sea several
small valleys reach the coast, but landward retreat of the
coast has left them abruptly truncated, as at Nash Point. 
Extensive sand dunes occur to the north of the Ogmore
River at Merthyr Mawr Warren and at Kenfig Burrows north
of Porthcawl.  Dune erosion is a problem along parts of this
coast (Carr & Blackley 1977).
2.6.2  Further sources of information
A.  References cited
Allen, J.R.L., & Rea, J.E.  1987.  Late Flandrian shoreline oscillations
in the Severn estuary: a geomorphological and stratigraphical
reconnaissance.  Philosophical Transactions of the Royal Society of
London, 315: 185-230.
Arber, E.A.N.  1911.  The coast scenery of north Devon.  London, Dent.
Carr, A.P., & Blackley, M.W.L.  1977.  Topic report : Swansea Bay
(SKER) Project. Institute of Oceanographic Sciences Report, No. 42.
Steers, J.A.  1969.  The coastline of England and Wales.  Cambridge
University Press.
B.  Further reading
Edmonds, E.A., McKeown, M.C., & Williams, M.  1975.  British
regional geology: south-west England.  London, HMSO for
Institute of Geological Sciences.
Kidson, C.  1960.  The shingle complexes of Bridgwater Bay.
Transactions of the Institution of British Geographers, 28: 75-87.
Kidson, C.  1977.  The coast of south-west England.  In: The
Quaternary history of the Irish Sea, ed. by C. Kidson & M.J. Tooley.
Geological Journal (Special Issue), 7: 257-298.
C.  Contact names and addresses
Type of information
Contact address and telephone no.
Coast protection: England
*Ministry of Agriculture, Fisheries
and Food, Flood and Coastal
Defence Division, London, 
tel: [phone]
Coast protection: Wales
*Welsh Office Environment
Division, Cardiff, tel: [phone]
Geomorphological 
Coastal Geology Group, British
information for region; 
Geological Survey, Keyworth,
1:50,000 scale maps
Nottingham  NG12 5GG, 
tel: [phone]
*Starred contact addresses are given in full in the Appendix.
Region 11  Chapter 2  Geology and physical environment
38

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