Coasts Flashcards
(193 cards)
What is weathering?
Weathering is the wearing down or breaking of rocks by biological, chemical or physical processes.
What is mechanical weathering?
Breakdown of rocks into smaller pieces without changing their chemical composition.
What occurs in mechanical weathering?
Rocks are broken down by physical processes like freeze-thaw weathering.
At what angle does swash occur and what causes it?
Swash is driven by the prevailing wind, and travels in the same direction
At what angle does backwash occur and what causes it?
At a right angle to the direction of the beach, as it is caused by gravity
Give three characteristics of destructive waves
Wave crest is high, weak swash, strong backwash
Explain why destructive waves cause coastal erosion
Their strong backwash removes sediment from the coast
Give three characteristics of constructive waves
Wave crest is low, strong swash, weak backwash.
Explain why constructive waves can build beaches up
More sediment is deposited through the strong action of the swash than is removed by the weaker action of the backwash.
What occurs in freeze-thaw weathering?
Water enters cracks in rocks. The water freezes and expands. The crack expands. The ice melts and fills up the now larger crack. The process repeats until the rock breaks apart
What effect does mass movement have on a coastline?
Leads to the coast moving further back/retreating as cliffs gradually wear away. Can lead to the formation of beaches, marshes and dunes
What is erosion?
When land or rocks wear away due to action of natural forces like waves
How does erosion occur by hydraulic power?
As waves smash into rocks, they force air into them which causes cracks to form
How does erosion occur by abrasion?
Small particles in the water rub against the rocks, wearing them away
How does longshore drift occur?
Longshore drift occurs when waves approach the beach at an angle. The swash moves material up the beach, while the backwash carries it back down at right angles due to gravity. This process gradually shifts material along the beach and links erosion and deposition. Material is transported through suspension, traction, solution, and saltation.
What occurs in coastal transportation?
Material is moved from one place to another
Explain how the headland and bay have formed.
The coast is made of bands of more and less resistant rock. The waves erodes the less resistant rock faster than the more resistant rock. The eroded area forms a bay. The more resistant area sticks out to form a headland
What is deposition?
When sediment being carried by the water is dropped
Why are sandy beaches likely to form in bays?
Sandy beaches are often found the sheltered bays where waves lose energy, and their capacity to transport material decreases resulting in material being deposited.
What is the zig-zag movement of material along the shore by wave action called?
Longshore Drift
Identify your case study location for landforms of coastal erosion.
The case study location will be identified e.g. Flamborough Head / Durdle Door / Old Harry Rocks
Do headlands form along concordant or discordant coastlines?
Headlands form along discordant coastlines
What is coastal transportation?
The movement of sediment and beach material through wave action.
What is a wave-cut platform?
A wave-cut platform is a wide, gently sloping surface found at the base of the cliff and extends into the sea.