Coasts Flashcards
Costal erosion- Attrition
Materials carried in the sea hit against each other causing them to get smaller and smoother
Costal erosion- abrasion
Materials carried by the sea are hurled at cliffs by waves causing them to be worn down
Coastal erosion- hydraulic action
When air is forced into the cracks in the rocks causing them to explode which loosens the rock causing it to break off
Costa erosion- corrosion
Weak acids in the water along with salt cause the rock to weather, dissolving rocks along the coast
Speed of erosion will depend on
-rock resistance
- degree of joint
- angle of dip of bedding planes
- waves
-weather
How are bays formed
Soft rock is eroded faster by waves approaching to shore.
Soft rock is eroded by abrasion and hydraulic action (explain both in full)
How are headlands formed
Hard rock is left sticking out.
The bays are sheltered, and they erode faster. Due to it being sheltered deposition will occur
How are stacks formed
Erosion processes - hydraulic action, abrasion, corrosion, attrition (explain in full)
Rocks containing weak points are easily eroded.
A blowhole can form in the roof of the cave, as air is compressed causing verticale erosion.
Erosion occurs on the both sides of the headland due to wave refraction, until it cuts all the way through forming an arch.
Erosion enlarged the arch.
The base of the arch is undercut by erosion causing it to be unsupported.
Eventually the arch collapses due to gravity to form a stack. For example old harry.
Explain Costal transportation LSD
Prevailing winds make the waves wash into the beach at an angle, this is the swash.
The waves return to the sea at a 45’ angle this is backwash. Material in returned to the sea, due to gravity.
The backwash returns at 90’ to the beach and small material will be carried the longest distance.
How is a sand bar formed
Sand bars are formed by LSD.
Swash is where waves push material up the beach at an angle due to prevailing winds. Backwash is dragged back down the beach at right angles due to gravity. Bars form when there is a change in the coastline, causing a sheltered area to form allowing for deposition and material collects and begins to appear above the water. Bar developments are deposition is greater than erosion. A bar forms when a spit reaches the other side of a bay creating a lagoon behind it. This happens when there is a weak flow of water coming from the river to the sea.
Terminal moraine
It’s a ridge across the valley
Made up of unsorted glacial deposits
Glacier acts as a bulldoze as it moves downhill pushing material to the front of the glacier
It marks the furthest point that the glacier reaches
Once it melts it forms a natural dam
