Coasts Flashcards
To get 100% in the upcoming test (18 cards)
What is the fetch of a wave?
The distance it travelled.
What is the swash of a wave?
How far a wave washes up the shoreline.
What is the backwash of a wave?
When the wave retreats back into the sea.
What are destructive waves?
Waves (large) that erode coasts, so have a stronger backwash than swash.
What are constructive waves?
Waves (low and gentle) that deposit material onto coasts, so have a stronger swash than backwash.
What is hydraulic action?
When water and air is forced into cracks in rock. The pressure gradually weakens the rock, causing it to break up.
What is corrasion/abrasion?
When waves pick up loose rocks and hurl them against the base of a cliff, gradually wearing it away.
What is solution?
When salts and acids in sea-water react with rocks like limestone, slowly dissolving them.
What is attrition?
When loose rocks and pebbles carries by waves crash into each other, making them smaller and rounder.
What makes areas of coasts erode faster?
Stronger waves or waves striking an area of coastline frequently, windy weather making bigger waves and a softer rock type being easier to wear down.
What is longshore drift?
When material from one area of the coast is removed and deposited in another area from waves approaching at an angle then receding directly backwards.
What is the effect of longshore drift?
Larger particles that take up more energy are deposited further up the beach and smaller particles and deposited further down (sorted deposits).
What is the process of longshore drift?
Waves approach the beach at an angle due to the direction of prevailing winds driving them, then it picks up material and pushes it at the same angle, depositing material it doesn’t have the energy to carry, and taking the rest with it when it recedes due to gravity.
How is a stump formed?
Erosion such as corrasion/abrasion and hydraulic action erodes weak parts of a headland to first widen a crack, then form a sea cave, then an arch, which collapses into a detached stack. Finally, the stack wears down into a stump.
What is differential erosion?
When waves erode soft rock quicker than hard rock. Cliffs made up of varying rock types have jutting out sections of tougher rock, forming headlands, and curving inwards sections forming bays.
What are prevailing winds?
The most frequent wind direction in a certain area.
How is a spit formed?
When longshore drift carries material into the same direction it travels, but as it runs out of energy, it will continue to deposit the material into open water, and extend the beach outwards.
What is the difference between a sandspit and a tombolo?
A sandbar is when a spit obstructs seawater, trapping it between the land and itself, forming a lagoon, with more material deposited by wind and vegetation transforming it into dry land over time. A tombolo is when a sandspit connects an island to dry land in a bridge.
