Jncc coastal Directories Project Region 11 The Western Approaches

Sub-cell 7b: Trevose Head - Hartland Point
This part of the coastline is characterised by long stretches
of boulder-strewn beach separated by beaches of fine sand.
There is low northward littoral drift, but waves have a
stronger influence upon sediment movement.  There is dune
erosion in Padstow Bay and Bude Bay and erosion of
boulder clay overburden in Bude Bay.
Sub-cell 7c: Hartland Point - Morte Point
The Barnstaple Bay sub-cell shows littoral drift into a
sediment sink in the south-eastern corner of the bay, with
low eastward drift of sediment from Hartland Point to
Westward Ho!  Both waves and tides affect sediments in the
mouth of the Taw-Torridge Estuary.  There is erosion at a
number of places, including the Westward Ho! shingle
ridge, as well as at Braunton Burrows, Putsborough and
Woolacombe.  Croyde and Morte Bays have sediment
movement that is independent of that in Barnstaple Bay.
Sub-cell 7d: Morte Point - Sand Bay
Morte Point is a littoral-drift divide, and sediments east of
the point move eastwards towards Bridgwater Bay, which is
a sediment sink.  Beach sediment ranges from boulders,
pebbles and shingle in Porlock Bay and between Watchet
and Stert Point, through sand to mud.  Erosion occurs in
many places along the relatively low, soft cliffs between
Minehead and Hinkley Point, and there is dune erosion at
Brean.  Tidal currents and wind affect the sediment regime
in Bridgwater Bay as far as Sand Bay.
Sub-cell 7e: Sand Bay - Sharpness
The coastline of this sub-cell is alluvial, dominated by
mudflats and saltmarshes.  There is no appreciable drift and
little wave action, although serious erosion can occur when
high tidal levels coincide with storms.  
Sub-cell 8a: Wellhouse - Lavernock Point
There is little drift in this sub-cell, other than a weak drift of
pebbles northwards from Lavernock Point towards Penarth.
The coastline is alluvial, dominated by mudflats and
saltmarshes.
Sub-cell 8b: Lavernock Point - Worms Head
The rocky foreshore as far as Nash Point gives way to sandy
beaches further west.  Littoral drift, including of the shingle
along the high tide line at Porthkerry, is low to moderate
and predominantly eastwards.  The low cliffs between Barry
and Southerndown are suffering erosion, as are the beaches
and dunes around Porthcawl and Kenfig.  Short-term
(annual) sediment changes are minimal between Cardiff and
Region 11  Chapter 2  Geology and physical environment
32
E
E
E
E
E E
E
E
E
E
E
E
E
E
E
E E E E E
E
Morte Point
Hartland
Point
Land’s
End
Lizard
Point
Nash Point
Worms Head
Lavernock
Point
Sand Bay
Bridgwater Bay
Sharpness
Wellhouse
Porthkerry
Stert Point
Watchet
Porlock Bay
Bude Bay
Padstow Bay
Trevose Head
Rame Head
7e
8a
8b
7d
7c
7b
7a
6e
6d
Net drift direction
Drift divide
Cell or sub-cell boundary
Variable net drift direction
Sediment sink
Erosion
Partial or one-way drift
E
Region 10
Region 12
Map 2.4.1
Sediment transport and coastal cells.  Source: Motyka & Brampton (1993).  Adapted with permission from MAFF Flood and
Coastal Defence Division.  

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Merthyr Mawr: drawdown of the beaches occurs as a result
of storms but much of the sediment is reinstated on the
beaches during subsequent calmer intervals.  
Estimates of cliff recession rates along the South
Glamorgan coast have been made using historic maps,
evidence from the positions of Iron Age forts and
measurements of cliff-top retreat over an eight-year period
(Williams & Davies 1987).  The results show considerable
variation, with Nash Point estimated to be retreating at
around 2-11 cm/year.  On average, retreat along this coast is
estimated at roughly 1-8 cm/year, occurring as a series of
discrete cliffs falls: local rates, measured over a short time,
may be much greater. 
2.4.3  Further sources of information 
A.  References cited
Harris, P.T., & Collins, M.  1988.  Estimation of annual bedload flux
in a macrotidal estuary: Bristol Channel, UK.  Marine Geology,
83: 237-252. 
Motyka, J.M., & Brampton, A.H.  1993. Coastal management -
mapping of littoral cells.  Oxford, HR Wallingford.  (Report SR
328.)
Williams, A.T., & Davies, P.  1987.  Rates and mechanisms of coastal cliff
erosion in Lower Lias rocks.  Proceedings of a speciality conference on
advances in understanding of coastal sediment processes New
Orleans, Louisiana May 12-14, 1987.  New York, American Society
of Civil Engineers.  (Coastal Zone 87, Vol. II.)
Williams, A.T., Morgan, N.R., & Davies, P.  1991.  Coastal Zone 91,
Vol. 3: Proceedings of the Seventh Symposium on coastal  and ocean
management, Long Beach California, July 8-12, 1991.  New York,
American Society of Civil Engineers.
B.  Further reading
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.
Coastal Research Group, Glasgow University Department of
Geography and Topographic Science.  1994.  Coastal processes
and conservation.  Taw Torridge.  Peterborough, unpublished
report to English Nature.
Institute of Estuarine and Coastal Studies, University of Hull.  1995.
Coastal processes and conservation: the Fal. Peterborough,
unpublished report to English Nature.
Mouchell, L.G., & Parners Ltd.  1995.  Shoreline Management Plan for
coastal sediment sub-cell 6e: Lizard to Land’s End. Bristol,
NRA/Penwith District Council.
Rendel Geotechnics.  1995.  Coastal planning and management: a
review of earth science information needs.  London, HMSO.
C.  Contact names and addresses
Type of information
Contact address and telephone no.
Coast protection policy and
*Ministry of Agriculture, Fisheries 
sediment cells: England; 
and Food (MAFF), Flood and 
Shoreline Management Plans  Coastal Defence Division, London, 
for sub-cells in the region 
tel: [phone] 238 6855
(see also 
section 10.2.7
)
Coast protection policy and 
*Welsh Office Environment 
sediment cells: Wales
Division, 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
tel: [phone]
*Starred contact addresses are given in full in the Appendix.
2.4  Sediment transport
33

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