Flashcards
Coastal Landscapes & Processes
Cards in this deck (42)
- 1What three things affect the size of waves?1) The distance the wind has been travelling over the water (fetch)
2) The speed the wind is travelling
3) The length of time the wind has been blowing - 2What are the two types of waves?Constructive and destructive
- 3What are constructive waves?Constructive waves are smaller waves that have a more powerful swash than backwash. As a result they deposit material on the beach.
They break infrequently – 10 waves or fewer per minute
They are long in relation to their height
They are usually found on gently sloping beaches - 4What are destructive waves?Whereas destructive waves are larger waves that have a more powerful backwash than swash. As a result they take material away from the shore (eroding the beach).
They break frequently – between 10 and 15 waves per minute
They are high in relation to their length
They are usually found on steep beaches - 5What is the swash?The movement of water up the beach
- 6What is the backwash?The water returning back to the sea
- 7What is the fetch?The distance that wind travels over open water
- 8What is longshore drift?Longshore drift is the movement of sand and pebbles down a coastline.
It creates landforms on a coastline such as beaches, spits and bars. - 9Explain the process of longshore driftThe direction of the prevailing wind determines the direction of the waves hitting the coastline.
If the wind is blowing at an angle to the beach, the waves will transport sands and pebbles at the same angle (swash).
The waves always return to the sea in a straight line at 90° (backwash) as the water is being pulled by gravity, and so takes the shortest route back down the beach.
Material is moved along the beach in this zig-zag pattern until it meets an obstruction, or there’s a change in direction of the coastline. - 10Explain rock typesA hard rock (e.g. Limestone) will be eroded slowly, whilst a softer rock (e.g. sands and clays) can be eroded very quickly.
- 11Explain jointing/faultingJoints are small natural cracks in the rock and faults are larger cracks that are caused by tectonic movement. The more faults and joints a rock has the more susceptible it is to erosion, both from coastal and sub-aerial processes. Limestone is a good example.
- 12Explain coastal rock arrangementA coastline with rocks that run parallel to the coast is called a concordant coastline. One that has rocks running at right angles to the coast is called a discordant coastline.
- 13How do waves affect the rate of coastal erosion?Waves are the main cause of erosion on coasts.
Their power is determined by two factors:
Speed of the wind
Fetch – the distance over which the wind blows over open water.
The stronger the wind and the longer the fetch the more powerful the waves . This results in greater coastal recession. - 14How does the slope of the beach affect the rate of coastal erosion?As the waves approach the coast, they begin to lose energy due to friction with the beach.
The more gentle the beach’s incline (slope) the more energy the sea will lose.
On steep beaches the wave keeps most of its energy until it reaches the beach and so forms a destructive wave. This results in greater coastal recession. - 15How does the type of rock on the coastline affect the rate of coastal erosion?If the cliffs are made from resistant (hard) rock like granite, they will erode more slowly than cliffs made from less resistant (soft) rock such as clay.
If the cliff has a rock structure that has many faults and joints, such as Limestone, then it can erode more quickly due to the erosion of these lines of weakness.
Cliffs that are gentle with lots of vegetation will be less affected by mass movement (slumping and soil creep) and physical weathering than cliffs of bare rock. They will, therefore, be more stable and so less easily eroded by the sea. - 16What is weather?The day to day changes in temperature and precipitation (rainfall).
- 17What is climate?The average temperature and precipitation figures for an area.
- 18What is seasonality?A pattern of change in the UK’s weather between spring, summer, autumn and winter.
- 19What is prevailing wind?The most common wind direction. In the UK it’s from the south-west.
- 20How does seasonality affect the rate of coastal erosion?The seasonality of the UK's weather and climate affects the rate of coastal erosion. For example, in the winter the differences between night and day temperatures can cause freeze-thaw (mechanical) weathering on cliff faces. This weakens the cliff and accelerates erosion.
- 21How do storms affect the rate of coastal erosion?Storms also have an impact on coastal landforms. e large waves are powerful agents of erosion, resulting in coastal recession. The human coastal landscape, such as sea defenses, is in need of constant repair due to the increasing occurrence of storms
- 22How does prevailing wind affect the rate of coastal erosion?The prevailing wind in the UK is from the south west. The coastlines of Cornwall and Devon experience winds that may have blown for thousands of km across the Atlantic Ocean. These winds have a long fetch. The longer the fetch, the larger the wave (more destructive). Destructive waves have a greater backwash than swash and so take material away. They erode the land more quickly. These winds also bring warm, moist air from the Atlantic and frequent rainfall, which contributes to weathering and mass movement on the coast.
- 23What landforms are caused by erosion?Headlands and bays
Cliffs and wave-cut platforms
Caves, arches, stacks and stumps - 24Which landforms are formed by deposition?Beaches
Spits
Bars - 25What is a beach and how is it formed?A beach is an area of land between the low tide and storm tide marks and is made up of sand, pebbles and, in some places, mud and silt.
Beaches are formed when eroded material is transported by longshore drift and deposited by constructive waves along the coastline. - 26What is a spit and how is it formed?A spit is a long, narrow stretch of pebbles and sand which is attached to the land at one end, with the other end stretched out into the sea or across a river estuary.
Spits forms when longshore drift occurs on a coastline. - 27What is a bar and how is it formed?A bar is a ridge of sand or shingle which forms across the mouth of a river.
If a spit develops in a bay, it may grow across it, linking two headlands, forming a bar. - 28How are headlands and bays formed?Headlands and bays form on coastlines where there are rocks of varying resistance (hardness) and lie at right angles to the sea (discordant coastline).
Headlands stick out because they are more resistant rock (e.g. limestone) and so at first are not as quickly eroded by processes such as hydraulic action.
Bays are indented because they are less resistant rock (e.g. clays and sands) and so at first are more quickly eroded by the sea, e.g. by abrasion and hydraulic action.
Headlands end up experiencing the more powerful waves and so a faster rate of erosion so far because the waves are slowed down in the bay as they have to travel over a longer area of beach (this absorbs the waves energy) and the water is more sheltered from the wind, whereas the headlands stick out and so start to experience the more powerful waves. The waves are also refracted towards the headlands. As a result they are eroded more quickly than before. - 29How is a cliff formed?When the sea erodes the base of the cliff by hydraulic action and abrasion (as well as corrosion if the rock type is limestone or chalk), it undercuts the cliff and forms a wave cut notch.
The remains of the cliff rock, now below the sea at high tide, form a rocky wave-cut platform. There will be some boulders which will have fallen from cliff on to the platform.
An overhang will form above the notch. The overhang will be weakened by weathering and will eventually fall into the sea due to its own weight and the pull of gravity.
The sea will continue to attack the cliff and form another notch, and the new overhang will eventually collapse. As a result the cliff will retreat becoming higher and steeper. - 30How is a wave-cut platform formed?Wave-cut platforms form when destructive waves hit against the cliff face, causing an undercut between the high and low water marks.
- 31How is a stump formed?The sea will erode the fault due to processes such as hydraulic action.
As a result, over time the fault will widen forming a cave.
If the fault is on a headland then caves are likely to form on both sides.
Eventually the caves will meet, and an arch is formed.
The sea continues to erode the bottom of the arch, forming a wave-cut notch, and weathering will also take place on the rock face.
The top of the arch will collapse under the pull of gravity and weathering, leaving a column of rock called a stack standing on its own.
Further erosion and weathering of the stack will result in the formation of a stump that can only be seen at low tide. - 32How has industry affected coastal landscapes?Harbours were built to give shelter to fishing boats, which involved the building of jetties into the cliffs.
Large ports developed to import materials. These were usually on large estuaries, which had a major visual impact on the area as well as causing environmental changes. - 33How has urbanisation affected coastal landscapes?Original wetland areas were drained to ensure that the settlements were not flooded, meaning that wading birds and other animals lost their habitat.
During the early 20th Century, tourist developments along the coast led to further change to coastal landscapes.
These human activities/developments need defending from the sea (both erosion and flooding), and so a range of sea defences have been built, such as sea walls and groynes. These interfere with natural processes, such as groynes trapping material being moved by longshore drift. - 34How has agriculture affected coastal landscapes?Parts of the coastal landscape are still mainly farming areas. Such areas are less developed, meaning that the coastal landscape is largely unchanged and the natural processes are not interfered with, because the land is not seen as valuable enough to defend.
However, many lowland coastal landscapes that were originally wetland areas have been drained and used for farming. For example, Cuckmere Haven in Sussex was drained for farming, which changed the land-use from wetland to sheep farming. However, the coastal defences are no longer being repaired and so the area will gradually return to salt marsh as the sea gradually reclaims it. - 35How has coastal recession affected people?Loss of homes. This will have a major impact on daily lives and finances because there would be a loss in the money that had been invested in the home. E.g. loss of homes on Beach Road in Happisburgh on the North Norfolk coast.
Loss of farm land. This could impact on the viability of the farm as fields are lost where crops were once grown. E.g. the loss of farmland due to flooding at Porlock Bay, Somerset.
Disruption to communication networks – roads and railway lines – creating difficulty for commuters. E.g. disruption to the main railway line into the South West of England along the coast at Dawlish, Devon.
Decreasing value of properties as there’s a high chance they will be damaged by the sea, or will be lost to the sea. As a result there’s also difficulties in obtaining home insurance. E.g. the average cost of houses on Beach Road in Happisburgh, Norfolk, have fallen from £80,000 to just £1!
Cliffs become dangerous for walkers. This could affect local peoples’ quality of life as well as affect the tourism industry.
Loss of life from drowning - 36How has coastal recession affected the environment?Loss of land, and therefore wildlife habitat. For example, cliffs along the National Trust area known as Golden Cap, close to the village of Seaton in Devon, have receded by 40m in the past 20 years. This means that animals and birds are losing their breeding grounds, for example, Sand Martins breed on the soft cliff faces.
Visual pollution is also caused by the destruction to buildings and infrastructure on top of the cliffs.
The sea can be polluted by building materials drifting out to sea. This can also harm wildlife.
Increased deposition further along the coast.
Some areas are being left to erode and flood (a strategy of ‘managed retreat’ has been adopted). This can create new wildlife habitat for wading birds as a positive.
The contamination of water supplies and the sea by sewage water. - 37What is the difference between hard and soft engineering?Hard engineering involves major construction works and so is often more expensive and has a greater impact on the environment.
Whereas soft engineering options do not involve major construction works. Some believe they are more sustainable as they often have less impact on the environment. - 38Give three examples of hard engineering, as well as advantages and disadvantages of them.Rip-rap – large rocks placed in front of the cliff: Advantages - Reduces wave energy
Can be very cheap -£300 per metre
Effective for many years
Disadvantages - Not effective in storm conditions
Unattractive
Recurved seawalls – walls usually made from concrete, with a recurved face:
Advantages - Reflect and absorb wave energy
Effective for many years
Disadvantages - Expensive to build - £3000 per linear metre
Ugly – puts off tourists
Groynes - usually made of wood; stretch from coastline into the sea:
Advantages - Effective for many years
Prevents longshore drift – sand builds up on one side of the groyne.
Disadvantages - Unattractive and can make it difficult to walk along the beach
Disrupt the natural processes working on the beach such as longshore drift. - 39Give three examples of soft engineering, as well as advantages and disadvantages of them.Beach replenishment – the placing of sand and pebbles on a beach:
Advantages - Looks natural
Provides a beach for tourists
Disadvantages - May affect plant and animal life in the area.
Requires constant maintenance; can be washed away in as little as a year.
Cliff re-grading – the cliff is cut back and given a new gentle slope to stop it slumping:
Advantages - May be covered in eco-matting to encourage vegetation growth
Very natural – will encourage wildlife in the area.
Disadvantages - Not effective alone – needs other defences at the cliff foot
Some homes on the cliff may have to be demolished.
Managed retreat – allowing the sea to gradually flood land or erode cliffs.
Advantages - Creates new habitats for plants and birds
Cheap
Disadvantages - Upsetting for landowners who lose land
Difficult to estimate the extent of sea movement, especially with rising sea levels. - 40Give examples of how Dawlish Warren spit is an important resource for people and the environment.In 2000 - The spit was designated a Local Nature Reserve. It provides a habitat for birds and plants – it’s internationally important for wading birds and wildfowl.(ENVIRONMENTAL)
The spit is a popular tourist destination, with the resort attracting 480,000 visitors a year. (ECONOMIC) - 41Give examples of human factors changing the Dawlish Warren spit.In order to protect the spit and the surrounding infrastructure, a number of sea defenses were built.
The first wooden groynes were installed on the beach in 1959. It was hoped that they would trap material being carried by longshore drift, building the beach. The larger beach would absorb the waves energy, reducing the amount of erosion to the dunes. - 42Give examples of physical factors changing the Dawlish Warren spit.Storms throughout the 1960s continued to erode the sand dunes, threatening the spit’s habitat, tourism industry and function as a breakwater for the Exe Estuary.
The Spit has continued to change due to erosion and deposition. High spring tides accompanied by strong winds (storm surges) have driven waves across the ridge that forms the spit’s southern and eastern extents.
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- Year 9 Geography (Physical Geography) Flashcards on Coastal Landscapes & Processes , created by Jamie Etu-Menson on 30/08/2019.
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