Coastal Landforms & Landscapes (Edexcel A Level Geography): Flashcards
Exam code: 9GE0
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- FrontMarine Erosion
Define coastal erosion.
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Cards in this collection (41)
Define coastal erosion.
The wearing away of rock and sediment along the coast by waves, leading to the formation of distinct landforms such as cliffs and wave-cut platforms.
Define abrasion (corrasion).
Sediment and stones carried by waves are thrown against cliffs, scraping and grinding the rock surface, causing it to wear away.
Define hydraulic action.
The force of waves compresses air in cracks in the rock, increasing pressure and gradually weakening and widening the joints.
Define corrosion (solution).
Weak acids in seawater chemically dissolve soluble rock such as limestone and chalk, removing material from the coastline.
During winter, more waves increase erosion on many UK coasts.
During winter, more destructive waves increase erosion on many UK coasts.
How does lithology affect coastal erosion rates?
Coasts made of weak, heavily jointed rocks erode quickly, while resistant, massive rocks erode slowly, producing different landforms and cliff profiles.
Define wave-cut platform.
A gently sloping, rocky surface at the base of a retreated cliff, exposed at low tide, formed by repeated cliff undercutting and collapse.
What is a wave-cut notch and how does it form?
A hollow at a cliff base formed where destructive waves, using hydraulic action and abrasion, erode the rock at high tide level.
True or False?
Wave refraction concentrates energy on headlands.
True.
Wave refraction bends waves so they slow in shallow water and focus energy on projecting headlands, increasing erosion there.
At a headland, joints widen into a , then an , then a .
At a headland, joints widen into a cave, then an arch, then a stack.
Define fetch.
The distance over which the wind blows across open water, controlling how much energy a wave can gain.
How do constructive waves shape a beach?
They have strong swash and weak backwash, so they deposit sediment, building up a wide, gently sloping beach profile.
True or False?
Destructive waves have strong backwash and steepen beach profiles.
True.
Destructive waves have weak swash and strong backwash, removing material from the upper beach and often creating a steeper profile in the short term.
Define longshore (littoral) drift.
The movement of sediment along a coast by swash moving up the beach at an angle and backwash returning at right angles, creating zig-zag transport.
What are the four main types of sediment transport in water?
They are traction, saltation, suspension and solution.
In longshore drift, moves sediment up the beach, and moves it back down at right angles.
In longshore drift, swash moves sediment up the beach, and backwash moves it back down at right angles.
How do tidal range and tidal currents affect sediment transport?
A larger tidal range creates stronger tidal currents, which can transport more sediment, especially near estuaries.
True or False?
Deposition at the coast usually happens when waves gain energy.
False.
Coastal deposition usually occurs when waves lose energy, for example as wind slows, depth decreases or the coastline changes direction.
On high energy coastlines, and shingle are deposited, whereas low energy coastlines build beaches.
On high energy coastlines, large rocks and shingle are deposited, whereas low energy coastlines build sandy beaches.
Define drift-aligned beach.
A beach where longshore drift moves sediment along the shore because waves approach at an oblique angle to the coastline.
Define spit.
An extended ridge of sand or shingle projecting out to sea, formed by longshore drift where the coastline changes direction and deposition occurs.
How does a lagoon form at the coast?
A lagoon forms when water is cut off from the sea behind a bar, tombolo or barrier beach, creating a shallow enclosed water body.
A joins mainland to an island, while a joins two headlands.
A tombolo joins mainland to an island, while a bar joins two headlands.
True or False?
Salt marshes often develop in sheltered water behind spits and barrier beaches.
True.
Salt marshes form in sheltered, low-energy areas behind spits or barrier beaches, where fine sediment accumulates and salt-tolerant plants colonise.
Define plant succession on sand dunes.
The progressive colonisation of sand dunes by pioneer plants followed by other species, gradually stabilising the dunes and developing a dune ecosystem.
Define sediment cell.
A stretch of coastline within which sediment movement is largely self-contained, with linked sources, transfers, stores and outputs forming a coastal system.
What is meant by a coastal sediment budget?
The sediment budget is the balance between inputs and outputs of sediment in a coastal system, ideally maintaining dynamic equilibrium.
Most coastal sediment comes from input, but erosion is also a major source.
Most coastal sediment comes from river input, but cliff erosion is also a major source.
Define weathering.
The breakdown of rock in situ, at its place of origin, by mechanical, biological or chemical processes.
What is mechanical (physical) weathering?
The breakdown of rock into smaller pieces by physical processes such as freeze-thaw, wetting and drying, salt crystallisation and exfoliation, without chemical change.
In freeze-thaw weathering, water in cracks and then to widen them.
In freeze-thaw weathering, water freezes in cracks and then expands to widen them.
In salt crystallisation, growing salt crystals the rock, causing it to .
In salt crystallisation, growing salt crystals exert pressure on the rock, causing it to break down.
What are the three main types of chemical weathering?
They are carbonation, oxidation and solution, each involving rock minerals reacting with water or gases to dissolve or weaken the rock.
Define mass movement.
The downhill movement of material under the influence of gravity, including processes such as landslides, slumping and rockfalls.
Name four key factors that influence mass movement.
Important factors include slope angle, water content, vegetation cover and rock or regolith type, as well as human activity and climate.
In a slide, material moves as one .
In a slide, material moves en-masse as one coherent block.
True or False?
Soil creep is a fast mass movement process.
False.
Soil creep is an extremely slow movement, often less than 1 cm per year, caused by repeated expansion and contraction of soil.
Define rotational scar.
A curved, un-weathered, un-vegetated surface on a slope, left behind after rotational slumping removes a block of material.
What is a talus scree slope?
A fan-shaped mound of rock debris from block-fall, accumulating at the foot of a cliff, usually with a concave profile.
True or False?
A terraced cliff profile is smooth and uniform.
False.
A terraced cliff profile is stepped, formed where different rock layers or fractures fail at different heights along the cliff.
A slump (rotational slip) leaves a indented surface on the slope.
A slump (rotational slip) leaves a curved indented surface on the slope.
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