DEV meet-up UiPath Document Understanding May 7 2024 Amsterdam
Raised beaches and estuaries 2011
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3. Britain’s Atlantis under the North Sea
Jonathan Leake and Joanna Carpenter
The Times, 2007
SCIENTISTS studying the North Sea have found the remnants of a lost landscape, complete with human
settlements, under up to 450ft of water.
They have mapped lakes, hills, salt marshes, coastlines and rivers, all now covered in water and silt but
which were once the homes and hunting grounds of early modern humans.
It was inundated more than 5,000 years ago as the ice melted after the last ice age, raising sea levels at a
rate that some scientists say will now happen again because of climate change.
“What is emerging from our research is a prehistoric landscape larger than Britain itself,” said Professor
Vince Gaffney of the Institute of Archaeology and Antiquity at Birmingham University, who led the
research.
He will reveal details of his findings at the British Association’s Festival of Science in York next week. He
will describe how his mapping project has found the remains of a great lake, known as the Outer Silver
Pit, lying 100 miles east of what is now the mouth of the River Humber in Yorkshire. The lake drained
what were then the greatest rivers in northern Europe, including the precursors of the Ouse, the Tweed
and the Elbe.
Just to the east of the lake lay the rolling Dogger Hills - now submerged but which have become the
foundations for the notorious Dogger Bank sandbank. They also inspired the archeologists’ name for the
lost landscape: Doggerland.
Such features emerged from seismic data collected by oil companies hunting reserves of oil and gas in
the North Sea.
Gaffney and his colleagues realised that although the surveys had been designed to study rock strata
hundreds or thousands of feet below the seabed, the same data could be used to look at the upper layers
too.
“The coasts, rivers, marshes and hills we found were, for thousands of years, parts of a landscape that
would have been familiar to hundreds of thousands of people and countless species of animals,” said
Gaffney. “Now it is all gone.”
http://www.timesonline.co.uk/tol/news/science/article2368630.ece
http://www.nature.com/news/2008/080709/full/454151a.html?s=news_rss
4. Long – term Sea Level Change
Sea levels have been fairly static since the last ice age
but many changes took place during the Quaternary
glaciation that reflected both advance and retreat of
ice. A typical sequence would run as follows.
For each stage, what effect would there be on sea
level? What landforms might be created?
5. Stage 1 – The climate begins to get colder, marking
the onset of a new glacial period, increasing the
amount of precipitation falling as snow. Eventually
this snow turns into glacial ice which acts as a store
for water and slows down the hydrological cycle.
6. Stage 2: The weight of ice causes the land surface to
sink. Such a movement is said to be isostatic and it
moderates the eustatic sea level change in some areas.
Stage 3: The climate gets warmer. Eventually ice
masses on the land begins to melt. This starts to
replenish the main store and sea levels begin to rise
7. Stage 4: As the ice is removed from some land areas
they begin to move back up to their previous levels
(isostatic readjustment). If the isostatic movement is
faster than the eustatic, emergent features are
produced such as raised beaches.
8. RAISED BEACHES – ISOSTATIC UPLIFT
(i.e. the localised change in sea level,
relative to the land)
There are many examples of these features
throughout Britain, particularly along the
West coast - this is because the area
experienced the greatest weight of ice
during the last Ice Age (about 10,000 years
ago).
During an Ice Age, the massive weight of ice
bearing down on a landmass caused it to
sink. Over time, as the earth's temperature
rose and the weight of ice decreased, areas
of land began to slowly rise back out of the
sea.
http://www.bbc.co.uk/scotland/education/geog/coastline/standard/physical/features/sea_level/?topic=raisedbeach
9. Eustatic sea level change (i.e. worldwide sea level change)
The global sea level has fluctuated widely in the recent geological
past. It stood 4-6 meters above the present during the last
interglacial period, 125,000 years ago, but was 120 m lower at the
peak of the last ice age, around 20,000 years ago.
http://www.giss.nasa.gov/research/briefs/gornitz_09/
10. An estuary is ‘the area of a river mouth which is affected by sea tides’. The
River Fowey Estuary in South West England was created by eustatic sea level change.
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12. Raised beaches
When sea levels fall, more of the coastline is revealed.
Beaches, no longer combed by wave are left stranded and
exposed above the new sea level.
These features are called raised beaches.
The lower part will often show signs of marine erosion,
and a small cliff may be formed.
Any former cliff-line is also left stranded. No longer
undercut by the sea if becomes a degraded cliff. Over time
it will often become clothed in shrubs and bushes – a sure
sign of physical inactivity.
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14. Raised Beaches
Common around the coasts of western Scotland where three
levels have been recognised at 8m, 15m and 30m. Differential
uplift?
On the west of the Isle of Arran there is a raised coastline with
relict cliffs, arches, stacks and caves including the King’s Cave
(see next slide).
The beach is around 4 or 5m above present sea level. This
suggests that the sea has fallen to its present level but we know
that sea levels have raised considerable since the end of the last
ice age.
So how did they get to their present level?
15. Scotland: Caves, formed by the action of the
sea, now exist above sea level on a raised
beach
Norway: Raised wave-cut platform
16. Tectonic Activity raised beaches – e.g Turakirae Head, New Zealand
A series of storm beach ridges at Turakirae Head, near Wellington, indicate successive
uplift of the southern end of the Rimutaka Range during major earthquakes. The ridge very
close to the shore is the present storm beach ridge. Next inland is the ridge that was raised
6.4 metres in 1855. Further inland is a ridge dated at about 2,300 years ago, and the faint
ridge near the base of the hills is dated at about 5,000 years ago.
http://www.teara.govt.nz/en/historic-earthquakes/3/5
17. Estuaries
An estuary is ‘the
area of a river
mouth which is
affected by sea
tides’. The
River Fowey
Estuary in South
West England
was created by
eustatic sea level
change.
18. Estuary Formation
HOW DOES THIS DIFFER FROM A
DELTA?
The Lower
Course of a
river valley
has been
RAISED VALLEY SIDES DROWNED
by a rise in
sea level or
a fall in the
USING YOUR ATLAS land level.
FIND AN ESTUARY
(LOOK AT THE RIVER THAMES)
19. Estuaries
The effect of a relative rise in sea level is to flood the
coast. Deltas, spits and beaches will all disappear
under water.
Broad river estuaries known as rias are formed as the
flood plains are inundated.
They frequently have a number of branches as
tributary valleys are also flooded.
The land often rises steeply directly from the water’s
edge, which may be marked by a small cliff feature.
If the land has also been glaciated a fjord is formed.
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24. Chesapeake Bay Estuary in the United States is an example of a drowned river
valley (known as a ‘Ria’) which has formed an estuary.
