GCSE Geography - Coasts - Salt Marshes and Keyhaven Case Study PowerPoint

Looks at what salt marshes are, how they are formed, and the problems the habitat can have. Also, a case study - Keyhaven - and a quiz.

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  • Created by: Emma
  • Created on: 27-04-11 16:51

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Slide 1

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Salt Marshes
and Keyhaven Case Study…read more

Slide 2

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What are salt marshes?
· A salt marsh begins when mud and silt begins
collecting at a sheltered part of the coastline, where
deposition can be deposited, but the area is too
sheltered for the tide to pull it away.
· The deposition builds up over time meaning that the
mud breaks the surface to form mudflats.
· Some plants begin to grow: the first plant is
Cordgrass. It is tolerant to sea water and its long
roots help keep the mud and sediment together.
· These plants are called pioneer plants.…read more

Slide 3

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What are salt marshes?
· Due to the mud rising, it gets covered by the tides
less. This and rain will wash out some of the salt.
· As the salt is now lower in concentration, it means
more plants can start to grow in the more fertile soil.
· These new plant species include plants like sea
asters. These are known as the second generation.
· Over time, bigger and hardier plants will grow, until
in the end, marsh uplands form, that have trees as
well as plants.
· This is known as vegetation succession.…read more

Slide 4

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Salt marsh diagram…read more

Slide 5

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Keyhaven marshes, Hampshire
· A salt marsh that is formed in the lee (behind) Hurst Castle
spit. It has lots of wildlife. Cordgrass, that grows on the
mudflats; sea lavender, a plant that is colourful enough to
attract wildlife; oystercatcher, a bird with long legs that feeds
in the marshes.
· But Keyhaven is under threat. It is between a low sea wall
(built to protect the mainland) and the approaching sea. Due to
rising sea levels, 6mm a year, the salt marsh is retreating 6m a
year under the water.
· Major storms mean the salt marsh is even under more threat.
There is the issue that the Hurst Castle spit could be breached
in a large storm, meaning the salt marsh would be left to the
open sea, and be washed away or made salty again.
· A storm in 1989 left 50 to 80m of the salt marsh open to the
sea. This area was eroded away in less than three months.
· There is also a threat from tourism, from walkers,
birdwatchers and photographers, as they are damaging the
area by parking, pollution and walking anywhere they want.…read more

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What's being done to protect Keyhaven?
· To stop the spit from being breached, in 1996 rock
armour and beach nourishment were applied to the
spit to increase the spit's height and width. These
cost £5 million; the spit hasn't been breached since.
· To stop the threat from tourism, there is careful
management of the area. There is a central car park
and designated paths so people can't wander all
over the place and damage it. It has also been made
an SSSI, a Site of Special Scientific Interest. This
means there can be no development and access is
limited and monitored.
· Unfortunately, there's not much that can be done to
keep the sea level down.…read more

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really useful, thanks !

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