fjF••¥*f
%F⑧¥¥gFFgj :p
WHAT CAUSES DEPOSITION? Size ranges from a few
II. EE.BR?EBIB.iFTTBkBBKH.1 -☒¥
COARSE
cm to a few metres MATERIAL
- energy of waves
- friction ÷
:*:#%¥¥.•→*: when in an area of reduced energy, or higher
friction, this is when the water will lose its capacity Backwash
to hold the material so it will drop its load combines to flush
out cusp
BEACHES
÷¥¥¥÷Ñ•¥¥±÷_¥¥•:
*i ÷ ÷¥* ÷i ÷÷:÷÷§
÷÷÷÷
Beaches form in sheltered environments, such
Fine material
:•÷ •*÷ ¥¥¥¥¥
as bays. When the swish is stronger than the deposited
LAGOON Incoming offshore
backwash, deposition occurs swash divides
BARRIER
"÷
ISLANDS
ON BEACHES SPIT Crescent shaped
BAY indentation
BAY BARRIER - they’re formed where
RIDGES AND RUNNELS BAR
Form parallel to the shoreline MAINLAND BEACH there is a junction
in the foreshore zone between sand and
- ridges are areas of the shingle
foreshore that are raised - once the curving shape
above the adjacent shore is created, swash is
BARRIER ISLANDS:
which dips into a runnel TOMBOLO concentrated in the small
naturally sandy
- runnels are disrupted by bay that forms in the
breakwaters that
centre of the cusp
channels that help to drain the form parallel to a flat
water down the beach BAR :
coastland
a ridge of material that is
ok connected to both ends of
the mainland
q ☒ Barrier islands form as
waves repeatedly
deposition sediment
TOMBOLO: parallel to the shoreline
A bar is created when there
a ridge of material
A
is a gap in the coastland with
linking an island with water in it SPIT :
the mainland - this is due to longshore drift An extended stretch of
carrying material across the beach material that projects
Takes place when a spit connects the front of the bay
out to sea and is joined to
mainland coast to an island.
- occurs due to longshore drift moving gas the mainland at one end
material along the coastline formed where the prevailing wind n,owns
- material is pushed up onto the beaches at an angle to the coastline, resulting in
at an angle when the swash brings it onto
longshore drift
the coastline at a 45 degree anfle
, swash aligned beach
Swash aligned
÷ ÷ ÷q•÷E-*B•a B•M•→:÷ :É÷ E•:¥÷É*E¥•*µiB←!•FMÑ•
Drift aligned beach -
beach - beach is
beach is oriented
parallel to the
obliquely to the crest of
crests of the
the prevailing winds
prevailing winds
:
- shoreline is controlled
- beach stays the
by longshore sediment
same
processes
- littoral rates are
- open systems in terms
zero
of longshore transport
- closed systems in
- spits, bars, cusps and
terms of longshore
tombolos are all features
transport
drift aligned beach of drift aligned coasts
, • •
IB.BA/M*ANH.iBiAHB.Ab# NH.B.IB.BA
DUNE FORMATION AND MIGRATION • •
saltation
the bouncing
- sand dunes form due to an initial build up of •
.
of particles
sand with the presence of a plant that allows • •
more sand to build up
WHAT IS CRUCIAL FOR SAND DUNES TO - the wind is responsible for the build up and
FORM ? movement of the sand dune
- Wide beach espoused at light tide
• •
•• •
• •
•
- dunes move by saltation and creep
- regular and plentiful supply of sand soil creep
rolling particles
- large tidal range
- Strong onshore wind PIONEER STAGE :
- shallow gradient - seeds blown in by the wind or washed in by the sea
- low precipitation and humidity (Sand must be - rooting conditions are poor due to conditions (salty, dry, strong winds)
dry) - wind moves sand in the dunes and allows rainwater to soak through
- adequate vegetation
- need debris on the beach to trap the sand BUILDING STAGE :
initially - plants trap sand and bind the roots
- decaying plants traps and absorb rainwater
VEGETATION - less hardy plants can now grow (those who need more specialist conditions)
Vegetation diversity is greater further inland - plants colonise in dunes
- more rich soil - sand changes from yellow to grey
- plant succession
- sand has high levels of salt and low levels of CLIMAX STAGE :
fresh water - talked plants and more complex species now grow
- only certain species can adapt and grow - plants for earlier stages die out due to competition for light and water
- overtime as these plants grow and die, the sand -when water table is reached, dune slacks can occur
condition will improve - plants which are specially adapted to be water tolerant grow here
VEGETATION SUCCESSION MOBILE DUNES FIXED DUNES
- maximum vegetation you can get in that environment
r"""÷É€¥→qi;÷
- requires the most specialised conditions
Yellow dune
- once this is reached there is no influx of new species Fore
Embryo dunes Grey dune
dunes Dune Dune
The conditions of sand : Strand/ slack slack
}
- dry drift line
- salty So plants must adapt
- mobile
- lacking in nutrients
if they are going to
grow Sea MrM_t
⑧g_-g_fc@s←tAqg@A heath/
FIXED DUNES
EMBRYO AND FORE DUNES
i YELLOW DUNES
woodland
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