1.3 Coastal Landscapes and Processes (Paper 1) Flashcards
(98 cards)
<p>What is a<strong>coast</strong>?</p>
<p>A part of land that joins the sea</p>
<p>What causes<strong>waves</strong>to form?</p>
<p>Wind blowing over the sea</p>
<p>What does the<strong>size</strong>and<strong>strength</strong>of waves depend on?</p>
<ul> <li>How strong the wind is</li> <li>How long it blows for</li> <li>How far it travels</li> </ul>
<p>Define<strong>swash</strong></p>
<p>Water rushing up the beach</p>
<p>Define<strong>backwash</strong></p>
<p>Water draining back down the beach</p>
<p>Define<strong>fetch</strong></p>
<p>The distance a wave has travelled</p>
<p>What are<strong>constructive</strong>waves?</p>
<p>Constructive waves are waves that have a very<strong>strong swash</strong>and aweak <strong>backwash</strong></p>
<p>Theybuildup the beach</p>
<p>How do<strong>constructive</strong>waves build beaches?</p>
<p>They deposit material withthe<strong>swash</strong>as the<strong>backwash is weak</strong>and leavesand and pebbles behind</p>
<p>What are<strong>destructive</strong>waves?</p>
<p>Waves that have a<strong>weak swash</strong>and a<strong>strong backwash</strong></p>
<p>They<u>pull pebbles and sand back down the beach</u>as the water retreats</p>
<p>What arethe<strong>features </strong>ofconstructivewaves?</p>
<ul> <li>Low</li> <li>Wave crests far apart</li> <li>Gentle sloping wave front</li> <li>6 - 8 per minute</li> <li>Gentle beach created</li> </ul>
<p>What are thefeatures of<strong>destructive</strong>waves?</p>
<ul><li>Tall</li><li>High frequency</li><li>Break close together</li><li>Up to 15 per minute</li></ul>
<p>What are<strong>marine processes</strong>?</p>
<p>Marine processes are the actions of waves. This includes <b>erosion, transportation & deposition</b></p>
<p>Which<strong>waves</strong>are associated with coastal erosion?</p>
<p>Destructive Waves</p>
<p>Define <strong>weathering</strong></p>
<p>Weathering is the breakdown of rock at or near the surface by the weather</p>
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<p>What is<strong>mechanical</strong>weathering?</p>
<p>Mechanical weathering is caused by physical changes such as changes in temperature, freezing and thawing</p>
<p>Water gets into cracks in rocks, freezes when the temperature drops below 0°C, prising the rock apart. When the water melts, a larger crack develops. Over time, this causes rocks to break apart</p>
<p>What is<strong>chemical</strong>weathering?</p>
<p>The weathering of rocks by chemicals is called chemical weathering. Rainwater is naturally slightly acidic becausecarbon dioxidefrom the air dissolves in it. Minerals in rocks may react with the rainwater, causing the rock to be weathered</p>
<p>Define<strong>erosion</strong></p>
<p>Wearing away of rocks by water, weather or ice</p>
<p>Listthe<strong>4</strong>main types of<strong>erosion</strong></p>
<ul> <li>Hydraulic action</li> <li>Abrasion</li> <li>Attrition</li> <li>Solution</li> </ul>
<p>Define<strong>hydraulic action</strong></p>
<p>Water being forced into cracks in the rock and breaking it up</p>
<p>Define <strong>abrasion</strong></p>
<p>Loose rocks (sediment) are thrown against the cliff by waves. This wears away at the cliff and chips bits of rock off</p>
<p>Define <strong>attrition</strong></p>
<p>Loose sediment that has been knocked off the cliff is swirled around by waves, colliding with other pieces wearing them into smaller smoother pieces</p>
<p>Define <strong>solution</strong></p>
<p>Seawater dissolves material from the rock due to its slight acidity</p>
<p>What is<strong>massmovement</strong>?</p>
<p>When rocks loosened by weathering move down slope under gravity. They can slide or slump</p>
What is slumping?
Slumping occurs after long periods of rainfall. The rain seeps through permeable rocks such as sandstone. At the junction where permeable and impermeable rock meet, the saturated soil slumps and slides in a rotational manner along a curved surface
This is common where cliffs are made of clay
What is sliding?
Sliding is movement along a flat surface, usually a bedding plane. Large amounts of soil and rock move downslope rapidly and cause a lot of damage
What is rock fall?
A type of mass movement where material breaks off the cliff and falls down the slope
How is sediment transported along the coastline?
Longshore drift
Describe how longshore drift works
- Waves approach the beach at an angle
- As waves break the swash carries material up the beach at the same angle
- The backwash carries material straight back down the beach under gravity
- This causes the material to move along the beach in a zig-zag pattern
What is deposition?
When the sea loses energy, it drops the sand, rock particles and pebbles it has been carrying. This is called deposition.
Deposition happens when the swash is stronger than the backwash and is associated with constructive waves
Defne landform
A feature in the landscape that has been formed by erosion, transportation and/or deposition
What factors influence the landforms found along a coastline?
Hard rock (resistant rock) - does not erode easily - likely to find headlands
Soft rock (less resistant rock) - erodes easily - more likely to be a bay
List some coastal landforms that result from erosion
How do headlands and bays form?
Where coasts are made from alternating bands of hard and soft rocks, destructive waves will erode the less resistant (softer rock) more to form bays and coves. The more resistant (harder) rocks sticks out into the sea to form headlands
Describe how a wave-cut platform is formed
- The sea attacks the base of the cliff forming a wave-cut notch.
- The notch increases in size causing the cliff to collapse.
- The backwash carries the rubble towards the sea forming a wave-cut platform.
- The process repeats and the cliff continues to retreat
How do caves, arches, stacks and stumps form?
- Resistant rock headlands have faults and joints
- Abrasion and hydraulic action widens the joints
- Waves make the joint wider to form a cave
- Waves erode the cave until it cuts through the headland to form an arch
- The arch is eroded until the roof collapses leaving a stack
- The stack eventually collapses leaving a stump
List some coastal landforms that form as a result of deposition
- Beaches
- Sand dunes
- Spits
- Bars
How do beaches form?
- The material may come from eroded cliffs or have been moved from a beach somewhere else
- Waves transport the material by longshore drift and deposit it
What is a bar?
A narrow ridge of sand or shingle that grows across a bay
How is a bar formed?
Longshore drift carries sediment along from a headland, depositing sediment further out from the headland. Over time, this line of sediment joins two headlands together; a bar is formed, cutting the bay off from the sea
Which feature lies behind a bar?
A lagoon
Why do spits have a hooked or re-curved end?
Spits have a hooked end as wind and waves changes the direction of the spit
What are spits?
Lond narrow ridges of sand and shingle stretching out from the coast
How is spit a formed?
- Longshore drift moves material along the coastline
- A spit forms when the material is deposited further out from the coastline
- Over time the spit grows and develops a hook as wind blows off the sea.
- Waves cannot get past the spit and a sheltered area develops behind it where silt is deposited to create mud flats and salt marshes
Which feature lies behind a spit?
A saltmarsh and mudflats
How are sand dunes formed?
- Wind carries sediment up the beach
- Obstacles on the beach encourages sand to build up
- Vegetation begins to stabilse the dune, encouraging more sand to deposit
- Overtime, the dunes migrate backwards, away from the sea
Which grass grows on sand dunes and holds them in place?
Marram grass
Name an example of a UK coastline that has major erosional and depositional landforms
Dorset Coast
Name some coastal features you would find at the Dorset coast
- Arch - Durdle Door
- Bay - Swanage Bay and Studland Bay
- Cave, Arch, Stack, Stump - Old Harry
- Bar and Lagoon - Chesil Beach and Fleet Lagoon
Name a coastline that is at risk of erosion and has coastal management strategies in place
The Holderness Coast
Why is the Holderness Coast at risk of coastal erosion?
- Strong prevailing winds creating longshore drift that moves material south along the coastline
- The cliffs are made of a soft boulder clay
Why does the Holderness coast need protecting?
- Fast eroding cost (nearly 2m lost each year)
- Strong prevailing winds carries sediment south
- Made of soft boulder clay
- Lots of towns along the coastline
- Important gas terminal located there
What management strategies are being used at Holderness?
- Mappleton - rock armour along base of cliffs and rock groynes to trap sediment
- Hornsea - sea wall and groynes
- Withernsea - sea wall, groynes and rock armour
What are the impacts of the management of the Holderness coast?
+ Mappleton is successfully protected from erosion
- Towns south of Mappleton have lost sediment due to groynes, therefore they are experiencing increased erosion
- Increased need to protecting at the Easington Gas terminal which has cost £6 million
What is meant by hard engineering of coastlines?
Man made structures that are used to reduce coastal erosion and flooding
Name a range of hard engineering strategies used to manage coasts
- Groynes
- Sea walls
- Gabions
- Rock armour
What are the benefits of hard engineering strategies?
- Usually immediately effective
- Long lasting
What is a sea wall?
Sea Walls are concrete or rock barriers placed at the foot of cliffs or at the back of the beach
They are curved to reflect waves back to the sea
What are the advantages of sea walls?
- Effective at stopping the sea
- Provides a promenade for people to walk along
What are the disadvantages of sea walls?
- Can look obtrusive and unnatural
- Very expensive and high maintenance at £10,000 per metre
What is a groyne?
A groyne is a wooden or rock structures built out to sea at 90 degrees to the coast
They trap sediment moved along the coast by longshore drift
What are the advantages of using groynes?
- Create a wider beach for tourists
- Provide structures for people to fish from
What are the disadvantages of using groynes?
- Can be seen as unattractive.
- Costly to build and maintain at £150,000 every 200m
- Can have knock-on effects further down the coast
What are gabions?
Gabions are wire cages filled with rocks that can support cliffs or act as a buffer against the sea
What are the advantages of gabions?
- Cheap to produce and flexible in design
- Can improve drainage of cliffs
- Will eventually become vegetated and merge into the landscape
What are the disadvantages of gabions?
- For a while they look unattractive
- Cages last 5 - 10 years before rusting
What is rock armour?
Piles of large boulders dumped at the foot of a cliff
The rocks force waves to break and absorb their energy
What are the advantages of rock armour?
- Relatively cheap and easy to maintain
- Can provide interest for people
- Often used for fishing
What are the disadvantages of rock armour?
- Rocks usually come from other parts of the coastline
- Can be expensive at £200,000 per 100 metres
- Rock don't fit with the local geology
- Can be obtrusive
What is meant by soft engineering of coasts?
Working with the environment or nature to reduce the impacts of the waves
Name a range of soft engineering strategies used to manage river flooding
- Beach nourishment and reprofiling
- Dune regeneration
- Dune fencing
What are the benefits of soft engineering strategies?
- Less expensive than hard engineering options.
- Usually more long-term and sustainable
- Less impact on the environment
Describe beach nourishment
The addition of sand or shingle to an existing beach to make it higher or wider
What are the disadvantages of beach nourishment?
- Needs constant maintenance unless structures are built to retain the beach
- Becomes costly in the long term
What are the advantages of beach nourishment?
- Replaces beach or cliff material that has been removed by erosion or longshore drift
- Beaches are a natural defence against erosion and coastal flooding
- Beaches also attract tourists
- Relatively inexpensive option
What is dune regeneration?
Marram grass is planted to stabalise damaged dunes and help them to develop
Fences are used to keep people away from these areas
What are the advantages of dune regeneration?
- Maintains a natural coastal environment that is popular with people or wildlife
- Relatively cheap at £200 - £2,000 per 100 metres
What are the disadvantages of dune regeneration?
- Time consuming
- Can be damaged by storms
- Unpopular with some tourists due to fencing
What is dune fencing?
Fences are built alond the seaward facing dunes to encourage new dune formation
What are the advantages of dune fencing?
- Minimal impact on natural systems
- Can control public access to protect other ecosystems
- Fairly cheap at £400 - £2,000 per 100 metres
What are the disadvantages of dune fencing?
- Can be unsightly
- Needs regular maintenance
Which form of sea defence is built to prevent the effects of longshore drift?
Groynes
What is managed retreat?
Controlled retreat of a coastline by allowing land to flood. This marsh land then becomes a protective strategy, protecting the land behind it
Describe the advantages of managed retreat?
- Flooded land is land of low value
- Encourages the development of beaches (a natural defence) and salt marshes (important for the environment)
- Cost is minimal
Why is managed retreat a popular form of coastal management?
- It is more sustainable in the long term as less money is spent on hard engineering
- Sea level rise due to climate change is forcing us to choose this option
Name a managed retreat scheme
Medmerry near Chichester, West Sussex
Why was the Medmerry managed retreat scheme needed?
- Low lying flat land used for farming and caravans was threatened by a sea wall needing repair
- Building a new sea wall was a very expensive option
- As the land was of low value it was decided to allow the sea to flood the land
What will the Medmerry managed retreat scheme create?
- A large natural salt marsh acting as a buffer with the sea
- This will protect surronding farmland and the caravan park
- Creates a valuable wildlife habitat which is attractive to visitors
What have been the impacts of cliff management at Mappleton?
- The rock groynes have stopped beach material being moved south from Mappleton along the coast
- However, this has increased erosion south of Mappleton. Benefits in one area might have a negative effect on another
What is the High Water Mark?
The high water mark is the point the highest up the beach that the sea level rises to
What is the Low Water Mark?
The low water mark is the point the lowest down the beach that the sea level falls to
What are the 4 types of transportation?
- Suspension
- Saltation
- Solution
- Traction
What is Suspension in transportation?
A suspension is where silt (sand, clay or other material) and sand particles are held in water (but not dissolved). The silt and sand particles are then transported along with the water
What is Solution in transportation?
A solution is where rocks that are soluble are dissolved by water (limestone and chalk in particular). They are then transported within the water
What is Saltation in transportation?
Saltation is where small sand and gravel particles bounce along the river bed or sea bed. They will travel in the direction of the flow of water
What is Traction in transportation?
Traction is where large rocks or large particles are dragged along the river bed or sea bed by the current
What are Concordant Coastlines?
Concordant coastlines have a layer of soft rock, then a layer of harder rock, then a layer of soft rock next to each other The sea's waves will only hit 1 type of rock when they meet the coast
What are Discordant Coastlines?
Discordant coastlines have alternating chunks of hard rock and soft rock at 90° to the coast. The sea's waves will hit both hard rock and soft rock when they meet the coast. Bays are usually created where the sea meets the areas of soft rock and headlands are created where the areas of hard rock are
