Chapter 12- Sea Flashcards
How are waves formed
Waves are formed by the wind
What is a fetch
It is a area of open sea over where the wind blows
What is swash
The water rushing up the beach
What is backwash
The water rushing back down the beach into the sea
Processes of coastal erosion
Hydraulic action- the physical force of the waves breaks material off the coastline
abrasion-any loose material is thrown by the waves against the coast
solution-some rocks are dissolves by water
attrition-stones that are carried by the water hitting off each other
Compressed air- when the waves crash against a cliff, air gets trapped in the cracks and joints of the cliff face and becomes compressed. When the waves retread the pressure is suddenly released. The process of compression and release is done till rock shatters
Explain longshore drift
Waves move up the shore at a angle matching direction of prevailing wind. When the wave breaks swash moves the load up shore and deposits. The backwash carries material back down to the shore. The movement follows the slope of the beach usually in a straight line
Explain a feature of coastal erosion and deposition
A bay is a wide, curved opening into the coast. A headland is a neck of highland that juts out into the sea
Example-bubbling bay ,malin head
Formed when different bands of rock along the coast. If the rock is soft it is eroded quickly by the process of hydraulic action and abrasion and a bay is formed. If the rock is harder it is eroded much more slowly and stands out as a headland. If the headland is big they shelter the bay and a small beach may form in a bay as material is deposited by the waves
Feature of coastal erosion
A sea cliff is a vertical of steep slope in the coast. Example- cliffs of mother
Waves erode a notch at a line of weakness in the coast between the high water mark and the low water mark. Overtime this notch grows larger due to hydraulic action of the waves undercutting occurs. The rock above the notch is lef without support and eventually collapses forming a cliff. Compression cause the rock on the cliff face to shatter and fall into the sea
Features of coastal deposition
A build up of sand and pebbles deposited by constructive waves between low and high tide levels
Donabate beach County Dublin, Tramore beach County Waterford
When the waves break the swash carries its load, both are fine and coarse material up the beach and deposits it’s on the shore. The backwash is weaker and drags finer material back towards the sea and the deposits come out of it on the foreshore. As a result finer beach material is found on the foreshore of the beach well coarser beach material is found at the back shore. Storm beach is formed during stormy weather when large rocks and stones are hurled past the normal high tide level by the swash. Sand dunnes build up at the back of a beach when the sand is dried out by the wind and is blown inland until it is trapped by a wall or vegetation
Name and describe two ways that the coast can be protected from the erosive power of the waves
Rock armour-these are large boulders at the base of a cliff or in front of dunnes. When a wave breaks its hits the rock armour and loses energy,which reduces erosion of the coastline. Rock armour is used to protect the coastline in County Waterford
Gabions- they are wire cages filled with small stones. They are placed in front of beaches or sand Doons to break the power of the waves and slow down erosion example County Clare,Lehinch
Name five other features of Sea erosion
Sea cave-it is a tunnel into a cliff
See arch- it is a arch shaped tunnel through a head land
Sea stump it is a pillar of rock cut of from a cliff/head land and left standing on its own when an arch collapses
Blowhole-a blowhole is a passage that links the surface of a cliff top with the roof of a sea cave
what is a sea cave
it is a tunnel into a cliff
what is a sea arch
it is an arch shaped tunnel through a headland
what is a sea stack
it is a pillar of rock cut out from a cliff/headland and left standing on its own when an arch collappses
what is an sea stump
it is when the sea stack eroded and crumbles
