Coasts Flashcards
What are the two types of waves?
Constructive: pushing effect, build-up of material. Forms a flat beach gradient. Low energy waves. Beach building: main process deposition. Low wave frequency, low wave amplitude, long wavelength. Strong swash. Weak backwash.
Destructive: pulling effect, carries away scoured material (drags it away, almost like digging). Forms a steep beach gradient. High energy waves. Beach scouring by breaking wave. Higher wave frequency, high wave amplitude, short wavelength. Weaker swash, stronger backwash. Material carried away by the waves, destroying the beach.
What is erosion?
The breakdown of material, its removal and transportation to another place where the ‘load’ (material being carried) is dropped or deposited (usually in a low energy zone). It is carried out by an agent of erosion (usually waves, also by rivers, rain, ice, wind).
What are the four main types of marine erosion?
Corrasion: this is the action of material carried by the wave, wearing away at the cliff face (sand-paper effect).
Attrition: the wearing down of rocks into smaller pieces as the bump into each other in the waves.
Solution: when sea water/waves dissolve rocks. Eg. Limestone.
Hydraulic action: the sheer power of the waves trapping air in cracks in the cliff, forcing them apart and breaking them up (air expands under pressure).
What affect the rate of erosion?
Type of rock: geology. Energy of waves. Age of cliff. Fetch of a wave. Cliff height and structure, lithology, gradient. Vegetation holding the cliff together. Aspect (direction the cliff is facing). I Weather, subaerial weathering. I Winds. Rockfalls, slumping, landslides: mass movement. Beach gradient. Frequency of waves. Biological factors including animals burrowing. Beaches: absorb wave energy. People's use. Eg. Trampling.
Draw a diagram showing the erosion of cliffs, notches and wave-cut platforms.
Labels:
Sea attacks ahead and undercuts the cliff, forming a wave-cut notch. Hydraulic action and corrasion (possibly solution depending on the rock type).
The sea attacks ahead rather than down, so after the cliff collapses and the rubble is carried away, a wave-cut platform is left.
Hard rock cliff. The sea attacks the base of the cliff. When it collapses, the line of the cliff retreats.
The weather weakens the top of the cliff (subaerial weathering).
Eventually the notch becomes larger and the weight of the cliff causes it to collapse.
What are headlands?
A point of land which protrudes into the sea.
What is a bay?
A geographical feature formed in soft rock due to erosion.
When are headlands and bays formed? Draw a diagram.
When there are two different types of rock with different resistance/hardness next to each other.
What are landforms on a headland formed by? Draw a diagram.
As the waves approach the headland, and the water becomes shallower, the waves break and refract around the headland. They focus their energy mostly around the headland, especially to the sides. These are points of high erosion.
Show the evolution of landforms on a headland with a labelled diagram.
Draw diagram.
