Coasts

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  • Created by: Spannah
  • Created on: 06-06-18 14:24
What are some inputs into the coastal system?
Energy, Sediment, Changes in sea level, Human activity
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What are some outputs from the coastal system?
Coastal landforms, Accumulations of sediment (above the tidal limit), loss of wave energy
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What factors influence wave energy?
Strength of wind, Length of time over which the wind blows, fetch
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How are waves formed?
Air moves across the water, frictional drag disturbs the surface & forms ripples. The water particles move in an orbital motion which changes to elliptical as water becomes shallower. The wavelength & velocity decrease, and height increases.
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How do waves break?
As they approach shallow water, friction with the sea bed increases and the base of the wave slows down. The height therefore increases and the wave becomes steeper until the top 'plunges' forward.
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How do the heights of constructive and destructive waves differ?
Constructive = low in height, Destructive = high in height.
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How do the wavelengths of constructive and destructive waves differ?
Constructive = long (up to 100m), Destructive = short
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How do the frequencies of constructive and destructive waves differ?
Constructive = low (6-8 per minute), Destructive = high (10-14 per minute)
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How does the swash/backwash of constructive and destructive waves differ?
Constructive = swash stronger, Destructive = backwash stronger.
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How do the beaches created by constructive and destructive waves differ?
Constructive = sand, sloping beach, often with berms, Destructive = shingle, steep beach.
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How can beaches and waves be an example of negative feedback?
Constructive waves are usually associated with gentle beach profiles, but cause material to be deposited, steepening the profile and encouraging destructive waves. These waves remove material, making the beach less steep. Dynamic equilibrium :)
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What happens during a spring tide?
The sun & moon are aligned with the Earth, increasing the gravitational pull and therefore the tidal range because there is a higher high tide & a lower low tide.
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What happens during a neap tide?
The sun & moon form a right angle with the Earth, so the gravitational pulls counteract each other, creating a lower high tide and a higher low tide and decreasing the tidal range.
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How does wave refraction take place?
Refraction is the distortion of wave fronts as they approach the indented shoreline. This causes energy to be concentrated at headlands, causing erosive features and depositional features to occur in bays.
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What is a sediment cell?
The distinct areas in which sediment movements occur, within which the inputs & outputs are balanced and the system is closed. There are 11 in the UK & they vary in size, some containing sub-cells.
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Whats the difference between marine processes and sub-aerial processes?
Marine processes are connected with the sea (e.g. waves, tides and longshore drift). Sub-aerial processes operate on land but affect the shape of the coastline (e.g. weathering, mass movement & runoff)
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What are the 4 main types of marine erosion?
wave quarrying, hydraulic action, abrasion/corrasion, attrition and solution/corrosion.
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What are the factors that affect the rate of erosion?
wave steepness, fetch, sea depth, coastal configuration, presence of a beach and human activity.
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What are the 4 types of transportation?
traction (rolled along sea bed at high discharge levels), saltation (small stones lifted by current & bounced at high energy levels), suspension (small particles carried in flow) and solution (dissolved materials carried within water)
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Explain the process of longshore drift
Waves approach the shore at an angle, so material is pushed up the beach with the swash. The backwash drags the material back down at a right angle to the beach. This continues creating a zig-zag movement of material along the beach.
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What are the main types of biological (sub-aerial) weathering?
Thin plant roots can grow through cracks in the cliff, water running through decaying vegetation becomes acidic, birds & animals dig burrows, marine organisms also burrow.
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What are the main types of mechanical (sub-aerial) weathering?
frost shattering (freeze-thaw) - water freezes & expands, salt crystallisation - crystals exert stresses causing it to break and wetting & drying - clay can crack & break (expand & contract)
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What are the main types of chemical (sub-aerial) weathering?
carbonation (CO2 in air absorbed by water to form carbonic acid. Cooler temperatures make this more effective), oxidation (e.g. iron - reaction makes more vulnerable), solution (dissolving)
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What are the main sources of sediment? (6 things)
rivers (fluvial), cliff erosion, longshore drift, wind, glaciers and offshore.
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What are the 7 types of mass movement?
Soil creep, mudflows, landslides, rockfalls, runoff, landslip or slump and solifluction.
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Whats soil creep?
A slow movement of individual particles downhill. It occurs in wet weather and is a creep/flow. The rate of movement is imperceptible.
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What is a landslide?
block of rock moves rapidly downhill along a planar surface, remaining largely intact. Often triggered by earthquakes or heavy rainfall which reduces friction.
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What is a mudflow?
Heavy rain can cause large quantities of fine material to flow downhill.
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What is a rockfall?
The sudden collapse or breaking away of individual rock fragments or a block of rock at a cliff face. occurs rapidly and is often triggered by weathering or an earthquake. Most common in steep cliffs of resistant rock.
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What is a landslip/slump?
Differs from a landslide in that the slide surface is curved rather than flat. Usually occurs rapidly and in weak, unconsolidated clays/sands
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What is runoff?
Runoff is a good link between the coastal system and the water cycle. small particles are moved downslope to enter the littoral zone.
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What is solifluction?
Similar to soil creep but specific to cold periglacial environments. In summer, surface layer thaws and becomes saturated because it lies above impermeable permafrost. Moves downhill by heave and flow.
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What is the difference between a concordant and discordant coastline?
A concordant coast has rock types parallel to the coastline, whereas a discordant coast has rocks perpendicular to the coastline (forming headlands and bays)
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What are the erosional landforms? (8 things)
headlands & bays, cliffs & wave-cut platforms, caves, arches, stacks and stumps.
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What are the depositional landforms? (7 things)
Beaches, spits, tombolos, offshore bars, barrier beaches, sand dunes and salt marshes.
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What is eustatic sea level change?
When the sea level changes due to variations in the volume of water in the oceans, and takes place on a global scale.
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What is isostatic sea level change?
When the height of the land changes, caused by variations in its mass, and takes place on a local scale.
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What is a Ria?
Rias are submergent features, and are created by rising sea levels flooding river valleys. They look similar to a normal river, but have more water in them.
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What is a Fjord?
Fjords are submergent features, and are drowned glacial valleys. They are much deeper inland than they are at the coast, unlike rias. they're long and steep sided, and have a U-shaped cross section.
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What are raised beaches?
Raised beaches are emergent features, and are areas of former wave-cut platforms & their beaches. Behind them, relic cliffs can be found, with caves, arches, stacks and stumps.
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What are the examples of hard engineering that you need to know?
sea walls, rock armour, gabions, revetments, groynes & barrages
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What are the examples of soft engineering that you need to know?
beach nourishment, dune regeneration, marsh creation, land use/activity management
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Other cards in this set

Card 2

Front

What are some outputs from the coastal system?

Back

Coastal landforms, Accumulations of sediment (above the tidal limit), loss of wave energy

Card 3

Front

What factors influence wave energy?

Back

Preview of the front of card 3

Card 4

Front

How are waves formed?

Back

Preview of the front of card 4

Card 5

Front

How do waves break?

Back

Preview of the front of card 5
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