features of deposition Flashcards
what are the features of deposition?
spits bars tombolos salt marshes sand dunes
how is a spit form?
it is a stretch of sand or shingle that forms when a coastline changes shape suddenly
material carried by longshore drift continues in that direction rather than following the coastline
as drift weaknes material is deposited
how is a recurved spit formed?
when the wind changes direction or through wave refraction
why does a spit usually form near an estuary?
as it promotes deposition due to the fact that the flow out water out to the sea is stronger
where are salt marshes usually found?
in sheltered areas away from wind and waves
behind spits are good environments
what are salt marshes an example of
haloseres
a succession in a highly saline environment
what conditions are needed for salt marshes to form?
- low energy environment
- a arge input of sediment
how is a salt marsh formed?
once the right conditions are in place
accumulation of sediment occurs over time due to it being a low energy enviro
this is known as sediment accretion
it starts to elevate and plants can then grow such as halophytic plants which either stabilise it
not as submerged
what is a sand dune an example of?|
a psammosere succession that develops in sands
what is needed for sand dunes to form
plenty of sediment
a strong continuous wind, facing the prevailing wind is the best
how is a sandmen formed?
an object such as rock or human rubbish is usually deposited in the high water mark
this means that sediment becomes trapped and deposits it then builds up and forms an embryo dune
as emrbyo dune grows it starts to get pioneer species colonise it turning it into a foredine
new embryo dune develops in front of the embryo dune
what is the order of succession in sand dunes?
embryo foredune grey dune dune slacks climax - end of succession
why do sand dunes need to be protected?
they are highly fragile environments which are easily damaged by humans
most methods are soft engineering
what is the example of a sand dune area that is being protected?
setoff sand dunes
what are the problems at sefton?
- large amounts of sediment are removed for commercial purposes such as glass polishing
- in the 1960/70s tourism became very popular in the area causing much damage
- dumping of toxic materials in the ecosystem
- ports built in liverpool have cause sediment carried by longshore drift to become stuck
