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Coastal Erosion
Timeline
10,000 BC - The dry valleys, ridges and escarpments
of the Eastbourne Downland were formed by glacial action
during the Ice Age. The chalk of the cliffs, however,
was formed over a period of 30 million years when a warm
sub tropical sea covered the area, between 95-65 million
years ago. The shells of billions of microscopic
planktonic algae formed a deposit which eventually
hardened into layers of white rock a thousand feet
thick. This has since been uplifted due to continental
movement and subsequent erosion has created the Downs
seen today.
8,000 BC - End of Ice Age as temperatures increase. Sea
levels rise and flood a valley to form the English
Channel, enabling the sea to flood through to the South
Downs. Marine erosion of cliffs begins. Mesolithic
hunter gatherers explore the region.
4,000 BC - Neolithic Man attracted to the well-drained
chalklands of the Eastbourne Downs which offer fertile
grounds for crops. The area is gradually cleared of wild
wood for grazing & crops. Flint tools from this period
have been found in the area and there is a Neolithic
causeway camp on Combe Hill upon the Northern
Escarpment.
2,000-1,500 BC - Bronze Age peoples clear woodland to create
space for settled agriculture - evidence of hut sites
and domestic pottery found near Belle Toute. Numerous
burial mounds, 'round barrows', are located upon the
escarpment ridges.
600 BC - New, Iron Age settlements indicated by numerous
field banks in area, particularly at Bullock Down and
near Jevington.
50 BC - Romans take control of south east England.
Increasingly efficient farming - remains of Roman farm
found on Frost Hill.
400 AD - Romans leave Britain. Eastbourne Downland used for
grazing.
1250 AD - Medieval farms and settlements established.
20th Century - Farm mechanisation and decline of traditional
farming methods. Increased demand for food leads to loss
of chalk grassland to intensive farming with the use of
artificial fertilisers. The loss of traditional
landscapes and habitats leads to the rise of the
conservation movement in the late 20th Century and the
protection of the Eastbourne Downland.
Chalk Grassland
The chalk grassland cover of the Eastbourne Downland
provides one of Britain's richest wildlife habitats with
up to 40 plant species growing in one square metre of
turf. The thin, poor quality soil encourages slow
growing plants and the long history of sheep grazing,
which continues today, has led to the development of the
springy turf.
The downland supports a wide variety of plants which can
only survive in chalky soils and also the butterflies
and other insects that these plants attract.
The Eastbourne Downland is conserved following the
decline of chalk grassland during the middle of the 20th
century due to increased food production and the use of
pesticides and other chemicals in arable farming. A
decline in grazing animals - sheep due to a decline in
sheep farming, and rabbits due to myxomatosis - meant
that much of the chalk grassland was taken over by
coarse grasses, scrub and pioneer woodland. After the
Second World War large areas of chalk grassland were
ploughed up for arable farming and in all 25% of the
chalk grassland of the South Downs was lost between 1966
and 1980.
Eastbourne Borough Council today employs shepherds to
tend the Council's flock of sheep which graze the Open
Downland in the traditional manner in order to preserve
and enhance it. Much of the tenant farmland is also now
under grass, with the farmers supported by grant aid
from the Ministry of Agriculture, Fisheries & Food (the
ESA Scheme).
Coastal Erosion
One of the most stunning aspects of the Eastbourne
Downland is the Heritage Coastline of pure white chalk
cliffs. The erosion of these cliffs by the sea is often
thought of as a destructive process but it is this
erosion which creates and maintains the cliffs'
magnificent whiteness through constantly eroding the old
cliff face and revealing the clean white chalk
underneath.
The white cliffs of Beachy Head and the Seven Sisters
have been eroding for at least 10,000 years, ever since
the end of the last Ice Age. The base of the cliff is
attacked with tremendous force at high tide as the waves
break against the chalk. Shingle is also thrown at the
cliff and pockets of air are trapped in the crevices and
alternately compressed and decompressed.
These forces combine to erode a notch in the base of the
cliff which eventually cannot support the upper parts of
the cliff. The cliff is also weakened from the top
during the winter as rain water in the soil freezes and
expands, pushing the rock apart, and then thaws and runs
through the crevices. A section of cliff then tumbles to
the beach, creating a temporary defence against the
waves until it is broken up and washed away.
One of the key conditions of the management of the
Heritage Coast is that it is left undeveloped in order
to preserve the landscape value. This means that no sea
defences will be built to slow the natural process of
erosion, not even to save existing buildings. Belle
Toute Lighthouse was moved back from the cliff edge on
March 24 1999 in order to save it from an imminent
collapse into the sea.
The Heritage Coast recede an estimated average of about
½ -1 metre a year. Occasionally there will be a larger
than average cliff fall, such as that on January 10 1999
when up to 6 metres of cliff edge tumbled away, to a
depth of 17 metres over a 70 metre long stretch. As
global warming continues and sea levels rise the rate of
erosion is expected to increase and falls of this size
will become increasingly common.
Credit to original source
of information located at the following site:
http://www.eastbourne.org/tourism/beachyhead/geology.php
Information from the British Geographical
Society:
http://www.bgs.ac.uk/esissues/beachy.html
Information from the Applied Geology Research Unit (AGRU) of
Brighton University.
http://www.brighton.ac.uk/environment/research/earth_systems/
agru/rocc_chalk_cliffs.htm
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