1.1.7 Aeolian, fluvial and biotic processes the characteristics and the formation of landform in coastal environments Flashcards
What is initially needed for a sand dune to form?
Sand dunes are small ridges or hills of sand found at the top
of a beach, above the usual maximum reach of waves.
They form from wind blown sand that is initially deposited
against an obstruction, such as a bush, driftwood or rock.
As more sand particles are deposited, the dunes grow in
size, forming rows at right angles to the prevailing wind
direction.
If vegetation such as marram grass and sand couch, begins
to grow on the dune, its roots will help to bind the sand
together and stabalise the dunes//
What role do pioneering plants play in the
succession of a sand dune?
coach gress - able to survive / cope in dry salty and exposeed conditions
marram grass is a typical species found in fore dunes they have long tap roots to seek water the growth of marram grass is stimulated by dunes
there roots grow in lateral direction. perfect for binding the endurance
as pioneer plants take hold they bind sand dune with vegetation
what is sand dunes and why are dunes vulnerable ?
Sand dunes can be important ecosystems supporting unique plant life and a healthy population of small animals and insects.
Dunes are very vulnerable to erosion by natural processes and by human activity. It is common to see vulnerable sections of dunes fenced off to prevent public access, or for paths to be laid to prevent people from eroding the dunes
Optimum conditions for a sand dune are?
An abundant supply of sand, usually sourced from the sea bed.
A low beach gradient.
A macro-tidal range that exposes the sand so it can dry out at low tide.
Strong prevailing onshore winds
Vegetation such as marram grass and sand couch, to colonise the dunes
once they have formed.
Which transportation type is most commonly
needed in the formation of a sand dune?
The initial movement of sand occurs when wind has reached the threshold to carry the sediment up the beach
Transportation occurs, with
the most common process
being saltation
For sand to be deposited
again, a reduction in wind
velocity is needed
Sand then accumulates quickly to form a foredune ridge. This is the basic requirement for a coastal dune system to form, depending on the availability of further sediment supply
If sediment supply is low then sand blown inland from the foredune may not be replaced, rendering the dune vulnerable to storm erosion and blowouts - not enough sand , fore shore will erode
Blowouts is the process by where pioneering plants are eroded off a dune probably due to their weakness still and an empty space is left in the dune. Parabolic dunes, which are U-Shaped crescents can form behind these blowouts.
How do parabolic dunes form?
If strong winds erode a section of the vegetated sand (commonly referred to as a blowout), a parabolic dune may form
Describe an estuarine environment
Estuaries are locations where rivers extend into the coastal zone. They result from
the interaction between marine and fluvial processes i.e. salt water and fresh water.
In the low energy environment of an estuary the dominant process is deposition, so
the estuary can be regarded as a sediment sink for sand and mud.
How do rivers help salt marshes to form?
salt marsh require a large input of sediment which can arrive from the sea and rivers.- near the tidal /mud flat
low gradient of a tidal mud flat means that any river that flow into it will very quicly deposit any sediement theyre transporting.
the periodic flooding of the tidal .mud by the tide will deposit even more sediment
How do spits help salt marshes to form?
salt marshes only form in low enrvgy environemnt where there is shelter from the wind and waves
depositional landforms , spits can help provide this shelter
How does accretion occur?
sediment accumulates over tiem and the elevation of the tidal flat increases - coastal accretion
How do pioneering plants help further accretion?
pioneer species such as spartina helop stabilise already deposited sediment
plants that grow on the salt amrsh are halophytic - love salts
and are capable of surviving underwater for several hour a day- pioneer species
pioneer plants include - spartina and salicornia - several adapttion not only help them thrive in saline environment also help aid coastal accretion. - helps with more deposition
the roots of spartina help stabilise already deposited sediment, aiding coastal accretion.
theyre invasive plants that spread quicly
coastal accretion takes place quicly and the elevation of the salt marsh increases greatly , creates new environments that are submerged by the tides for shorter period of time.
allowng even more species of plants and animals the salt marsh.
How do salt marshes affect human activity?
create a habitat for creatures and natural coastal defence
people like to build ports for boats on salt marshes
salt marshes like to develop where people like to sail
long plants get stuck on the propellers
trading brings more money than tourist.
what happened in park gate ?
in the past salt marshes grown uncontrabally and caused major economic changes to the area
park gate - small villages - on wirral peninsula was a major shippiing port for the uk. river Dees estuary silted up , shipping became less feasible and the area became a seaside resort.
throughout the 19th and 20th century grass began to grow on the bbeaches and a salt marsh developed .
park gate is a small tourist area knoiwn fro icecream
salt marsh is protected by RSPB - large number of nesting bird some delinquets set fire in 2013 killing rare creature
what happened in park gate ?
in the past salt marshes grown uncontrabally and caused major economic changes to the area
park gate - small villages - on wirral peninsula was a major shippiing port for the uk. river Dees estuary silted up , shipping became less feasible and the area became a seaside resort.
throughout the 19th and 20th century grass began to grow on the bbeaches and a salt marsh developed .
park gate is a small tourist area knoiwn fro icecream
salt marsh is protected by RSPB - large number of nesting bird some delinquets set fire in 2013 killing rare creature
How does human activity affect salt marshes?
salt marshes bad for business people try stop from developiong
remove plant specjes that are growign on the salt marsh and aiding coastal accretion
slows the salt marsh grown
once salt marsh fully developed hard to get ird of
new land - cities across the globe have encrouched onoto salt marsh
urban development kills anyting on sm - fre eland
agricultute activites they eat the sm
first drained , cattle can bbe herded on sm’
impacts the sm ecosystem as cattle selectively eat certain plants , reducing biodiveristy
run offf from fertillisers used on farmland enters the sm ecosystemm - fertilisers mixes with water - leading to eutrophication
fertiliser acts a phytoplankton causes population of phyloplankton to increase .
