Sea Flashcards
What plays a role in coastal changes
The power and action of the waves
How are waves created
Waves are created by wind blowing over the surface of the sea
What influences the size and energy of a wave
- how long the wave has been blowing
- the strength of the wind
- how far the wave has travelled (fetch)
What are the two types of waves
Destructive waves and constructive waves
What is a awash
When a wave breaks and water is washed up on the beach
What is a backwash
When the water runs back down the beach
What is a constructive wave
constructive waves build up the coats and their swash is stronger than the backwash
What is a destructive wave
destructive waves erode the coast and their backwash is stronger than the swash
What are the characteristics of a destructive wave, give 8
- they are created in stormy conditions
- they are created from big waves when a string wind has been blowing for a long time
- they occur when the wave has travelled a long fetch
- they have a stronger backwash than swash
- they have a short wave length and are high and steep
- are powerful
- have a steep sea bed
- more waves per minute
What are the characteristics of a constructive wave, give 7
- they are created in calm weather
- they break on the shore and deposit material, building up beaches
- they have a swash stronger than the backwash
- they have a long wavelength and are shorter in height
- are less powerful
- have a gentle sea bed
- fewer waves per minute
What is coastal erosion
The wearing away and breaking up of rock along the coat
What are the different ways destructive waves erode the coast
Hydraulic action, abrasion, attrition, solution
What is hydraulic action in coastal erosion
The force of the water breaking the rock cliff and sea bed down
What is abrasion in coastal erosion
When bits of rock and sand in waves grind down cliff surfaces like sandpaper
What is attrition in coastal erosion
When waves smash rocks and pebbles on the shore into each other, and they break and become smoother
Solution in coastal erosion
When acids contained in sea water dissolve some types of rock such as chalk and limestone
What are the features caused by coastal erosion (name 9)
Bays, headlands, caves, arches, stacks, cliffs, notches, wave cut platforms and stumps
How do headlands form
Headlands form along coastlines in which bands of soft and hard rock outcrop at right angles to the coastline. Erosion is more slower where there is more resistant rock, and the hard rock is left sticking out into the sea
How do bays form
Bays form where the rock is softer thus eroded faster and this leaves indents in the coastline between two headlands
How are caves formed
Weak areas of a headland are attacked by waves and are opened to form a cave
How do arches form
Caves are widened and deepened by erosion to form an arch
How do stacks form
As the roof of an arch is continually undercut it eventually collapses leaving an isolated stack
How do stumps form
When stacks are continually eroded ,eventually they will collapse to form a stump. Ships will be covered by water at high tide
How do cliffs form
Cliffs are steep rock faces along the coastline which are formed by abrasion
How does a wave cut platform form
When cliffs retreat they leave behind a sloping rocky platform that is exposed when at low tide
How does a wave cut notch form
When waves undercut the foot of the cliff, forming and indent
What features are formed by coastal deposition
Sand bars, spits, tombolos, lagoons
How do sand bars form
They are ridges of sand built offshore by destructive waves, they are either submerged or partly exposed
How do spits form
Spits are long stretches of sand joined to the mainland and on one end. It is formed when prevailing winds blow against an angle to the coastline, creating long shore drift
What is the prevailing wind
The usual direction of the wind in an area
What is a longshore drift
It is the movement of sand along the shore by wave action.It happens when waves approach the beach at an angle. The swash carries material up and along the beach
How do lagoons form
A lagoon forms when a sand bar or spit form across a river mouth. The river water separated from the sea by the sand is the lagoon
How do tombolos form
A tombolo is formed when a spit joins an island to the mainland
