Landforms of Coastal Deposition: Sand Spits, Sand Bars & Lagoons and Tombolos


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



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



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