Coasts - Full Flash Cards

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The Coastal System: Name 4 Inputs
Energy is inputted in the form of waves, wind currents and tides. These will vary spatially and temporally. Sediment from other eroded coastlines, rivers and sub-aerial processes will be deposited along coasts.
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The Coastal System: Name 4 outputs
Landforms, sediment and the shape and position of the coastline are all examples of outputs.
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The Coastal System: Name The processes that take place on coasts
wave action, tidal movement, erosion, weathering, transportation, deposition.
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What are coasts constantly being shaped by?
Waves, Tides, The ocean currents and Effects of the weather
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What happens whenwhen rock structures are MORE resistant or sheltered from prevailing wind and waves?
changes occur slowly
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What happens when rock structures are LESS resistant and are open to storm conditions and heavy rainfall?
sudden and dramatic changes can occur
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How are waves are created?
waves are created by wind blowing over the surface of the sea, creating friction, the energy in transferred which creates the waves
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What is wave height affected by
wave height is affected by the wind speed and the fetch of the wave
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What is the FETCH of a wave?
fetch= maximum distance of sea the wind has blown over creating the waves
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What happens when waves approach the shore?
As waves approach the shore they break, friction with the sea bed slows down the bottom of the waves and makes their motion more elliptical, the crest of the wave rises up and then collapses
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What is the difference between SWASH and BACKWASH?
water washing up the beach/force= swash water washing back= gravitational backwash
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What are the characteristics of Constructive Waves?
Build up beaches, long wavelength, they are long and low- gives more elliptical cross profile, swash is quickly absorbed by the beach because of the low levels of energy, sediment thrown up by the breaking waves accumulates in ridges or 'berms'
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What are the characteristics of Destructive Waves? (1)
High and steep, more circular cross profile, higher frequency (10-14 waves per minute), wavelengths are shorter,
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What are the characteristics of Destructive Waves? (2)
Wave breaks at considerable height creating a large amounts of energy which cannot be easily absorbed by the beach, powerful waves run up on the beach, the volume of water creating the opportunity for strong backwash to move sediment down the beach
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When do Storm surges occur?
Storm surges occur when the following factors collide; high tide, strong onshore winds creating high levels of wave energy, low pressure weather systems allowing the sea to expand.
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What can can add to the intensity of a storm surge and why?
The shape of the landscape, where the sea is 'pushed' into a narrow area between two land masses, it is forced to rise causing flooding in coastal areas
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What is sub-aerial weathering?
sub-aerial weathering describes coastal processes that are not linked to the action of the sea- includes freeze thaw and salt weathering
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Name 4 Coastal Processes?
marine erosion, weathering, human activity, mass movement and slumping
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Coastal Land forms: Describe the formation of Headlands & Bays
headlands and bays form where there are bands of alternating hard rock and soft rock at right angles to the shoreline, soft rock is eroded quickly, forming a bay, hard rock eroded less quickly so sticks out as a headland
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Coastal Land forms: Describe the formation of Cracks, Caves, Blow Holes, Arches, Stacks, Stumps (1)
weak areas in rock are eroded by the process of hydraulic action and abrasion to form a cave, weakness in the rocks at the top of the cave are picked out by hydraulic action forming a channel reaching the surface of the headland- blow hole
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Coastal Land forms: Describe the formation of Cracks, Caves, Blow Holes, Arches, Stacks, Stumps (2)
sea caves cut through the headland forming an arch, the arch collapses forming a stack, a stack continues to be eroded away resulting in a stump.
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Coastal Land forms: Describe the formation of Cliffs and Wave-Cut platforms
cliffs retreat due to the action of waves and weathering, weathering and wave erosion cause a notch to form at the high water mark, which eventually develops into a cave. rock above the cave becomes unstable with nothing to support it so it collapses
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Coastal Land forms: Describe the formation of swash aligned beaches
Forms when the waves approach the coastline parallel to the beach. The swash and backwash move sediments up and down the beach often creating a stable, straight beach with a longitudinal profile.
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Coastal Land forms: Describe the formation of Drift- aligned beaches
forms when waves approach the coastline at an angle and sediment is moved along the coast by the process of longshore drift
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Describe the process of Long shore drift
swash carries sediment up the beach, parallel to the prevailing wind. Backwash carries sediment back down the beach at right angles to the shoreline. When there's an angle between the prevailing wind and the shoreline this is repeated
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Coastal Land forms: Describe the Features of beaches - Berms and ridges of sand and pebbles
Berms and ridges of sand and pebbles (about 1-2m high) found at high tide marks, are formed by deposition of coarse material at the limit of the swash
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Coastal Land forms: Describe the Features of beaches - Runnels and grooves
Runnels and grooves in the sand running parallel to the shore are formed by backwash draining to the sea
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Coastal Land forms: Describe the Features of beaches - cusps
cusps are crescent shaped indentations that form on beaches of mixed sand and shingle, develop in areas where waves break parallel to the beach and where there's a large tidal range
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Coastal Land forms: Describe the formation of a spit (1)
longshore drift continues to deposit material across the river bank leaving a bank of sand and shingle sticking out into the sea. occasional changes in the dominant wind and wave direction may lead to a spit having a curved end
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Coastal Land forms: Describe the formation of a spit (2)
over time the recurved ends may be abandoned as the waves return to their original direction. The area behind the spit is sheltered from the waves and often develops into mudflats and salt marshes
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Coastal Land forms: Describe the Formation of bars
bars are formed when a spit joins 2 headlands together, can occur across a bay or across a river mouth, a lagoon forms behind the bar
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Coastal Land forms: Describe the Formation of sand dunes (1)
sand dunes are formed when sand deposited by longshore drift is moved up the beach by the wind. Sand trapped by driftwood or berms is colonised by plants and grasses e.g. marram grass. the vegetation stabilises the sand to accumulate there
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Coastal Land forms: Describe the Formation of sand dunes (2)
This forms embryo dunes. over time, the oldest dunes migrate inland as newer embryo dunes are formed- mature dunes
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Coastal Land forms: Describe the Formation of Salt Marshes (1)
salt marshes form in areas of sheltered water e.g. river estuaries or behind spits. As silt and mud are deposited by the river or the tide, mudflats develops. The mudflats are colonised by vegetation that can survive the high salt levels.
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Coastal Land forms: Describe the Formation of Salt Marshes (2)
The vegetation can also survive long periods of submergence by the tide. The plants trap more mud and silt, and gradually they create an area of marshland that remains exposed for longer and longer between tides.
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What is Sea level change?
sea level= relative position of the sea as it meets the land
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How does the sea level vary?
sea level varies on a daily basis with the tidal cycle. onshore winds and low atmospheric pressure systems also cause sea surface to rise temporarily
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How are rising sea levels evident?
Rising sea levels are evident when looking at drowned river estuaries (rias) or glacial valleys (fjords)= submergent coastlines
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What are Rias?
Rias- river valleys are partially submerged, have gentle long- and cross- profile. they are wide and deep at their mouth, becoming narrower and shallower the further inland they reach, e.g. milford haven in south wales
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What are Fjords?
Drowned glacial valleys- relatively straight and narrow with steep sides, they have a shallow mouth, they are very deep the further inland e.g. sognefjorden in Norway
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What are emergent coastlines?
falling sea levels can be seen by the evidence of raised beaches or cliff formations now seen inland from current positions
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What is Hard Engineering?
Hard engineering approaches tend to be expensive, last only a short amount of time, are visually unattractive and unsustainable. They often increase erosion in other places further down the coast
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Hard Engineering - Sea walls
Sea walls- curved, straight or stepped reinforced concrete walls. reflect waves back out to sea, preventing erosion of the coast, also acts as a barrier to prevent flooding.
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Limitation of Sea walls
Expensive to build and maintain, creates strong backwash which erodes under the wall
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Hard Engineering - Reventments
wooden or concrete structures, waves break against the revetments which absorb energy.
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Limitation of Reventments
expensive to build but cheap to maintain, create strong backwash
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Hard Engineering - Gabions
steel mesh cages filled with small rocks, absorb energy and reduce erosion.
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Limitations of Gabions
cheap but ugly
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Hard Engineering -Rip rap (rock armour)
large rocks placed at the foot of sea walls to absorb wave energy
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Strength and Limitation of Rip rap (rock armour)
absorb wave energy, fairly cheap BUT can shift sometimes in storms
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Hard Engineering - Groynes
wooden or concrete structure built at right angles to the coast. trap beach material transported by longshore drift creating wider beaches which slows the waves reducing their energy.
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Strength and Limitation of Groynes
Quite cheap to build BUT they starve down-drift beaches of sand. thinner beaches don't protect the coast as well, leading to greater erosion and flooding.
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Hard Engineering -Breakwaters
concrete blocks or boulders deposited off the coast. force waves to break.
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Limitation of Breakwaters
expensive and can be damaged in storms
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Soft Engineering - Beach replenishment
pumping sand or shingle back onto the beach to replace eroded material
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Soft Engineering - building bars
underwater bars reduce wave water
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Soft Engineering -beach re-profiting
changing shape of the beach so that it absorbs more energy and reduces erosion
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Soft Engineering -fencing/hedging
preserves the beach by reducing the amount of sand being blown inland
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Soft Engineering - replanting vegetation
planting grasses or salt-resistant plants to stabilize low- lying areas
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Soft Engineering - beach recycling
moving material from one end of the beach to the other counteract longshore drift
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Strengths of all Soft Engineering Strategies
less expensive, more environmentally friendly, resulting beach has amenity value which is important for tourists. May not be suitable in places which are very developed
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Other cards in this set

Card 2

Front

The Coastal System: Name 4 outputs

Back

Landforms, sediment and the shape and position of the coastline are all examples of outputs.

Card 3

Front

The Coastal System: Name The processes that take place on coasts

Back

Preview of the front of card 3

Card 4

Front

What are coasts constantly being shaped by?

Back

Preview of the front of card 4

Card 5

Front

What happens whenwhen rock structures are MORE resistant or sheltered from prevailing wind and waves?

Back

Preview of the front of card 5
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