Marine Erosion And Transportation Flashcards
Explain marine erosion:
Destructive waves erode the coastline, less resistant (softer) rock such as sandstone, but all rock will erode over time
What is hydraulic action?
The power of waves with no involvement of rocks at all, the pressure from the waves on this air causes the cracks and joint to expand, when larger loose blocks of rocks are eroded in this way, it is called wave quarrying
What is cavitation?
When waves are very large, high pressure aid bubbles in waves get trapped in the small cracks in the rock, this air bubble implodes generating a shock wave which weakens the rock
What is abrasion?
When breaking waves are wedging sediment and it eroded against the rock surfaces, also known as corrosion, depending on how much sediment is available in a particular area of the coastal system
What is attrition?
The size of the sediment particles reduce as sediment in the waves erode against one another
What is corrosion?
Acids in the sea water can also wear away the rock, also known as solution
Explain marine transportation:
When material I’m the sea arrives or is eroded from cliffs, transported by longshore drift along the coastline, constructive waves brining material inland from offshore or carried ro the coastline by river
What is traction?
Large rocks and boulders are rolled along the surface
What is suspension?
Tiny sediment is suspended just under the surface of the water
What is solution?
The sediment is dissolved and carried by the waves
What is saltation?
When small pieces of shingle or large sand grains are bounced along the seabed
Describe how Longshore Drift works:
Influenced by direction of the prevailing wind, waves approach the beach at an angle, as the waves break the swash carries material up the beach at the same angle, as swash dies away, the backwash carries the material down the beach at a right angle, the process repeat, transporting material along the beach in a zig-zag movement, offshore currents can contribute to the movement of sediment along the beach
Why does marine deposition occur when waves lose energy?
The wind slows or changes direction, the wave experiences friction, usually with sea floor as the depth decreases, when the coastline changes direction such as at an estuary or headland, it is gradual rather than immediate process
What can high energy coastlines carry?
Can deposit large rocks and shingle but maintain enough to carry smaller sediment particles, this is why they have rocky beaches eg. Brighton on the south coast
What do low energy coastlines deposits?
Low energy coastlines deposit smaller sediment due to low wave velocity, creating sandy beaches
What is wave quarrying?
The action of waves breaking against unconsolidated material, such as sands and gravels, waves scoop out the loose material in a similar way to the action of a giant digger in a quarry on land
