How is a longshore bar formed
Landforms of Coastal Deposition: Sand Spits, Sand Bars & Lagoons and Tombolos
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landforms of coastal deposition are
formed to to the transport processes of
longshore drift and the work of
constructive waves leading to deposition
the direction of waves is influenced by
the prevailing winds in an area
constructive waves approach the
shoreline at an angle the strong swash
pushes beach sediment such as sand and
shingle up the beach at an angle in the
same direction of the waves following
the gradient at the beach the weaker
backwash brings some material straight
out this continues over time in a
zig-zag pattern the coastal load of sand
and shingle is transported further along
the beach by longshore drift with
constructive waves the swash is stronger
than the backwash which results in more
sediment being deposited as longshore
drift takes place the process of
longshore drift Kaleta deformation of
land forms of coastal deposition such as
sands bits sandbars and lagoons and Tom
bolos a sand spit is a ridge of sand
which extends out from the mainland
across a bay the direction of the waves
influences the direction of longshore
drift if the coastline changes direction
deposition will begin to occur out into
the sea
this builds up over time as the process
of longshore drift continues eventually
this leads to the formation of a sand
spit the sand spit may curve inwards at
the end due to wave refraction low hills
of sand called sand dunes may develop on
the spit
Marylyn grass may grow which helps to
bind the sand together eventually the
sand dunes will become more stable and
support more vegetation an example of a
sand spit can be found at Glen Bay in
County Kerry a sandbar and Lagoon are
formed when a sand spit extends
completely across a bay this occurs due
to the continued process of longshore
drift
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sand dunes would marram grass may form
over time to give stability to the
sandbar once closed off a bay then
becomes a saltwater lake known as a
lagoon over time a marshland may form as
rivers enter the girl and deposit silt
and sediment an example of a sandbar on
lagoon can be found at trim or in County
Waterford and at Our Lady's Island in
County Wexford a tombola was formed on a
sand spit connects an island to the
mainland this occurs due to the
continued process of longshore drift the
sand spit extends outwards into the sea
and deposition builds up over time
eventually the sand spit may connect the
island and the mainland sand dunes work
marram grass may form over time to give
stability to the tombola a tombolo can
also form as longshore drift occurs and
sand extends back from the island to the
mainland deposition occurs the sheltered
water between the island and the
mainland
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an example of a tombolo exists at Sutton
in County Dublin howth was in Ireland
but the tombola are connected it to the
mainland the suburb of Sutton is located
on the tombola and as a population of
over 5,000 people the tombola can also
be seen at ohmy Island in Galway the
tombola is only visible at low tide and
provides access to ohmy Island for
residents and tourists and high tide the
tombolo disappears and the island is cut
off from the mainland
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