coasts Flashcards
(21 cards)
what is erosion
the breaking down of a substance
what is abrasion
when rocks erode by knocking against the bed and banks of a body of water
what is hydraulic action
the sheer force of water breaking something down
what is corrosion
when rocks are eroded as water gets into cracks and holes and dissolves the rock through chemical changes.
what is attrition
when rocks collide with eachother and break down
what is transportation
when a body of water picks up sediment and moves it from one place to another.
what is long shore drift
Waves approach the coast at an angle.
Swash carries sediment up the beach at an angle.
Backwash carries sediment down the beach with gravity – at right angles to the beach.
This creates a zig-zag movement of sediment along the beach.
what is deposition
when a body of water loses energy and drops its sediment
how do erosion, transportation and deposition create coastal landforms
erosion breaking down rocks, transportation moving the material along the shore, and deposition dropping it to create beaches, spits, and other features. These processes work together to shape the coastline.
describe basic cliff erosion
1 the base of the cliff is eroded through abrasion and hydraulic action
2 this forms a wave cut notch, which gets bigger and bigger
3 the cliff forms an overhang, which eventually gets too heavy and falls into the sea.
4 as the cliff recedes a wave cute platform is created, these are exposed at low tide.
5 the cliff moves back and the process is repeated.
describe cave formation
on both sides of a headland, it gets eroded by hydraulic action and abrasion. This eventually forms a cave.
describe arch formation
the cave keeps being eroded until eventually the water makes a hole that goes all the way through the headland, creating an arch.
describe stack formation
eventually, gravity causes the arch to collapse, leaving a large, pillar-like rock, this is called a stack.
describe stump formation
as the stamp gets eroded from both sides, it can’t support its own wight and collapses leaving a stump. This process repeats and the headland retreats.
what are some reasons for coastal management?
to protect houses and buildings
to protect coastal ecosystems
defence against rising sea levels
what are revetments?
sloping ramps that face the sea and absorb waves energy
what is rip rap?
large boulders piled up in front of cliffs or sea walls to physically stop waves
what are sea walls?
a concrete barrier that protects areas from flooding, they are curved to deflect high waves
what are gabions?
wire cages filled with rocks and stacked to form a barrier against breaking waves
what is an off-shore breakwater?
rock structures built parallel to the coast. They force waves to break before they reach the shore.
what are groynes?
wooden or concrete barriers built perpendicular to the beach, they trap drifting sand to create a wider beach
