Dune Formation. How are they formed?. Working in small groups, try to work out how the sand dunes shown in the picture developed?. TV Clip: BBC Learning Zone. Sand dune formation and movement - the Dune of . ID: 583749 Download Presentation
Dune Formation. How are they formed?. Working in small groups, try to work out how the sand dunes shown in the picture developed?. TV Clip: BBC Learning Zone. Sand dune formation and movement - the Dune of .
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Presentation on theme: "Sand"— Presentation transcript:
Slide1
Sand
Dune Formation
Slide2
How are they formed?
Working in small groups, try to work out how the sand dunes shown in the picture developed?
Slide3
TV Clip: BBC Learning Zone
Sand dune formation and movement - the Dune of
Pilat
Duration
: 05:29
The Dune of
Pilat
in France is the highest sand dune in Europe. The loose sand constantly moves and the dune migrates away from the sea until it meets a pine forest inland
.
Slide4
The Dune of Pilat: 500m wide, 3km long, 140m high.
Sand supplied from the Atlantic
The forest acts as a barrier
The initial / fore dunes are moving constantly away from the sea
Slide5
A sand dune needs the following three things to form:
1. A large amount of loose sand in an area with little vegetation2. A wind or breeze to move the grains of sand3. An obstacle that causes the sand to lose momentum and settle. This obstacle could be as small as a rock or as big as a tree.Where these three variables merge, a sand dune forms.
Activity: Draw a diagram to explain how a sand dune forms
Slide6
Beach at Low Tide
Sand
accumulates on the beach from
longshore
drift.
At
low tide, the sand dries out allowing the prevailing winds to move the loose sand up the beach.
If there is
a large tidal
range, then there is more time for the sand to dry out.
Slide7
Embryo Dune
Sand
needs an
obstruction
to accumulate around.
Seaweed
, dead seabirds, driftwood and other detritus may all serve this purpose.
Slide8
Fore Dune
The first plants to colonise the
foredunes
are
Apodasmia
similis
.
.
Slide9
Yellow Dunes
The yellow dunes begin to show a greater diversity of plants as conditions become more favourable. As plants die and decay, a humus layer builds up and this traps both water and nutrients.
Slide10
Mature Dunes
The most mature dunes are found several hundred metres from the shore. Left undisturbed these dunes develop a soil which can support shrubs and trees.
Slide11
Management
The dunes may eventually need to be protected by the local authority.
This
often means fencing off at least part of the dune
system.
This allows damaged dunes to recover and/or ecologically important sections to be protected.
Public
access to beaches may be via fenced-off pathways. Along the footpaths, information boards can be used to educate the public about why the dune system is important and how they can avoid damaging it.
