Work Of The Sea Flashcards
Waves
Erosion, transport, deposition
Constructive waves deposit more material than is taken away
Destructive waves cause erosion during stormy weather
A fetch is the length of sea over which the wind blows the waves
The material transported by the sea is called its load
Prevailing winds are winds that blow regularly from one direction
What is hydraulic action
Is erosion carried out by the force of the waves crashing or pounding against the coast. Air is trapped by incoming waves. As the pressure is released, this can cause a mini-explosion, which can weaken and shatter the rocks
What’s abrasion
The sea uses its load of rock and stones to erode the coast
What’s attrition
The sea’s load is worn down as the pieces smash against each other so that the stones are smoothed and made smaller
Bays and headlands
Bays and headlands are formed when the sea erodes a coastline with bands of hard and soft rock
The sea erodes the soft rock faster than the hard rock by hydraulic action and abrasion
Soft rock = bays
Hard rock = headlands
Sea cliffs
A cliff is a vertical height of rock along the coast
1) the waves erode and undercut the base of the cliff using hydraulic action and abrasion
2) a wave cut notch. is formed at the base of the cliff between the high and low water marks, which undermines the rock above
3) the face of the cliff falls down
4) a wave cut plate form is formed as the cliff retreats
E.g. Cliffs of moher co. Claire
Faults and joints
Are weaknesses in the rock
Widened by hydraulic action and abrasion
Cracks can be widened into waves
Arches
Are formed when two caves join back to back through headland
Sea stacks
are formed when the roof of the arch collapses
Sea stumps
Are the worn-down remains of a sea stack
E.g. Ballybunion, co Kerry
Swans and backwash
Swash - when swash is stronger than backwash, then the waves are constructive waves
Backwash - when backwash is stronger than the swash, then the waves are destructive waves, taking away material from the beach
Long shore drift
It occurs when waves (swash) hit the beach at an angle and retreat straight back down (backwash). This process transports materials along the coast in a zig zag fashion
1) the awash runs up the beach at an angle (diagonally) and deposits material
2) the material is brought back down by the backwash
The awash moves the material further along the beach. It forms features of deposition such as sandpits, sandbars and tombolos
To control longshore drift
Groynes are built at right angles to the coast
These trap sand as it is being transported along the beach by longshore drift
Sandspit
Is a landform mostly made of sand that is attached to the land at one end. It is mostly made of sand that is attached to the land at one end. It is formed by longshore drift, which deposits sand where the coast changes direction and the waves lose their power. This occurs at river mouths and headlands.
What is a sandbar
A sandbar is formed when a sandpit stretches across a bay and connects the two sides. This happens when there is no river flowing into the bay. The sandbar blocks off water behind it
