Coasts Flashcards
What is erosion
Erosion is the wearing away of the land by the sea and the material it carries
What is transportation
Transportation is the movement of eroded materials by the sea
What is deposition
Deposition is the laying down of materials carried by the sea
What is a headland
A headland is a part of the coast that sticks out into the sea and ends with a cliff
What is a bay
A bay is a wide curving inlet of the sea
How are headlands and bays formed
Headlands are made up from hard rock which erodes slowly, making the headland stick out into the sea. Contrary to headlands, bays are made from soft rock that erodes faster, making the bay curve inwards
Why can we usually find a beach at a bay
We can find a beach at a bay, because waves carry the eroded material from headlands into bays
How is a stump formed
A stump is formed through the erosion of a headland. Firstly, a small cave is formed in a headland by hydraulic action. The cave is further eroded and deepened, forming an arch. The arch is eventually undercut, resulting in it falling due to the lack of support and gravity. A stack is left behind, which eventually collapses, leaving behind a stump
What is a cliff
A steep slope overlooking the sea
What is a cave
A cave is an underground feature formed by erosion at the base of a cliff
What is an arch
An arch is a coastal feature made when waves erode through a headland
What is a stack
A stack is a pillar of rock formed after an arch is undercut
What is a stamp
A stamp is a rock remaining in the sea after a stack collapses
How does hydraulic action erode the sea
With hydraulic action, water is forced into cracks in the rock, compressing the air inside. When the wave retreats, the air blasts out, forcing the rock apart and widening the crack
How does corrasion erode the sea
With corrasion, loose rocks are thrown against the cliff by the waves. This wears away the cliff and causes bits of rock to fall off
What’s another name for corrasion
Abrasion
How does corrosion erode the sea
Corrosion is a type of chemical erosion. It occurs when the sea water dissolves material from the rock
How does attrition erode
Attrition erodes the sediment rather than the land. Rocks and pebbles that fell of due to hydraulic action are swirled around by the waves, causing them to collide with other sediment. This turns them into smaller and rounder sediment
What is a wave-cut notch
A wave-cut notch is an area undercut by erosion at the base of a cliff
What is a wave-cut platform
A wave-cut platform is a flat surface at the base of a cliff caused by erosion
How does a cliff retreat due to erosion
At the base of the cliff, hydraulic action forms a wave-cut notch. The size of it is determined by the distance between the high tide and the low tide. The wave-cut notch creates an on overhang, which eventually falls down due to gravity. As broken rocks are made smaller by attrition, they make the wave-cut platform smooth by corrasion. The process is repeated many times, causing the cliff to retreat and the wave cut platform to get wider
What is longshore drift
Longshore drift is the movement of materials along the coast by waves that approach the sea at an angle
Describe the process of longshore drift
Waves carrying materials move up the beach at angle due to the direction of the wind. The wave then moves straight down the beach because of the pull of gravity. This results in the materials moving in a zig-zag pattern
What is a groyne and what does it do
A groyne is a wall built perpendicular to the coast that prevents erosion and extends the land. It does so by stopping longshore drift and making sand pile up on the end of the groyne.
Why do hotels build groynes
Hotels build groynes as they block longshore drift, resulting in sand piling at the end of the groyne. This extends the land, allowing the hotel owners to build more
How do groynes affect the land on the opposite side of the groyne
Groynes block longshore drift and the material it carries. This results in all the carried material staying on the one side of the groyne. The lack of material coming to the other side causes the land to erode
What are parallel wave-breakers
Parallel wave-breakers are large rocks in the sea that force waves to break before they hit the coast. They absorb the energy of the waves and encourage deposition
What are the advantages/disadvantages of parallel wave-breakers
Advantages: effective, do not spoil the beach
Disadvantages: Expensive, hard to mantain
What are rip-raps/ rock armour
Rip-raps are large rocks placed on the coast to prevent erosion by absorbing the energy of the waves
What are the advantages/disadvantages of rip-raps
Advantages: Cheap, uses natural materials
Disadvantages: Allows some erosion, can be moved by large rocks
What is a seawall
A seawall is a wall build along the coast that prevents erosion by reflecting the waves and absorbing their energy
What are the advantages/disadvantages of a seawall
Advantages: Very effective
Disadvantages: Ugly, very expensive
