Coasts Flashcards
How do destructive waves (erosion) cut into the coastline in four ways?
*Hydraulic action - The sheer force of waves hitting the coast.
*Attrition - Material is carried by the waves and bomb into each other and are worn smaller and rounder.
*Corrosion - Seawater is slightly acidic which some types of coastal rock.
*Abrasion - Waves pick up material and hurl it at the coast.
What are the sources of the material in the sea?
*Eroded from cliffs.
*Transported by longshore drift along the coastline.
*Brough inland from offshore constructive waves.
*Carried to the coastline by a river.
How is material transported? (marine)
*Traction - Large heavy material is dragged along the sea floor.
*Saltation - Smaller materials bounce along the sea floor (leapfrog motion).
*Suspension - Fine materials are held in the water.
Solution - Dissolved material is carried in the water.
What is longshore drift?
It is the main process of transportation along the coast.
*Waves (that are influenced by the prevailing wind) approach the beach at an angle.
*As the waves break, the swash carries material up the beach at the same angle.
*Then, as the swash dies away, the backwash carries the material down the beach at right angles, due to gravity.
*The process repeats, transporting material along the beach in a zig-zag motion.
What happens if a coast is obstructed? - longshore drift.
If a coast in obstructed, sediment is prevented from moving and the area further along the coast is deprived of sediment.
What problems does a coast lacking sediment cause?
*Less sediment means smaller beaches which are less attractive to tourists, causing a loss of income.
*Less sidemen removes natural coastal protection against erosion.
