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Pressures on shingle habitats - summary
Shingle beaches are by their nature prone to movement under the action
of tides and waves. Where the sediment budget is in deficit this can lead to
erosion
and loss of the foreshore. These natural processes can be made worse where shingle
is extracted from the beach, as for example is the case at Cayeux-sur-mer
in France. Where erosion is occurring the most frequent reaction, where land
is threatened with inundation from the sea, is to erect some form of sea
defence structure. This may help retain the beach but can also damage
any vegetation, which might develop and have 'knock-on' effects downdrift of
the structure itself.
Shingle structures have also been subjected to a number of developments,
which destroy the surface shingle. Excavation
for aggregate and loss to buildings and other infrastructure
have adversely affected many sites. The structures include nuclear power stations,
housing, roads and airfields, mostly on stable structures. Recreational and
other activities, which alter the surface of stable structures have also taken
their toll destroying or disturbing surface vegetation. On some of the most
stable surfaces the imprint of human activity can remain visible for decades.
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Guidance: The fact that many shingle structures appear to be derived
from sources of sediment deposited at the end of the last glaciation make
them particularly vulnerable to erosion and loss. New sediment (from the
erosion of cliffs) is very restricted at most sites. The case of Hallsands
in Devon provides a salutary lesson in the dangers of removing these deposits.
When combined with stabilisation of eroding cliffs whole stretches of
coastlines can be adversely affected as on the coast of France between
the Seine
and the Somme.
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