Coastal processes Flashcards
The size and energy of the wave depends on certain factors:
The fetch (how far the wave has travelled)
The strength of the wind
How long the wind has been blowing for.
What are the two types of wave?
Constructive and destructive
Water that is rushed up the shore is known as..
Swash
The water that flows back towards the sea is known as…
Backwash
What are the 6 characteristics of Destructive waves?
Weak swash and strong backwash
Occurs in stormy conditions, with strong winds
The strong backwash removes sediment from the beach
The waves are steep and close together
Tall waves with short wavelength
High frequency (arriving quickly)
What are the 6 characteristics of constructive waves?
Small waves, with low wave height and long wavelength
Occurs in calmer conditions, less wind
Strong swash and weak backwash
The strong swash brings sediments to build up the beach
Backwash is not strong enough to remove sediments
Waves are low and further apart.
What are the three types of weathering?
Freeze thaw, biological and chemical.
How does freeze thaw weathering occur?
This happens when rock is porous (contains holes) or permeable (allows water through)
What is freeze thaw weathering?
Water enters cracks in the rock.
when temps drop the water freezes and expands, causing the crack to widen.
The ice melts and water makes it way deeper in the cracks.
The process repeats itself until the rock splits entirely.
What is biological weathering?
Plant roots can get into small cracks in the rock.
As the roots grow, the cracks become larger.
This causes small pieces of rock to break away.
How does chemical weathering occur?
Rainwater and seawater can be a weak acid. Rocks like limestone and chalk can, over time, dissolve by the acid in the water.
What is mass movement?
Mass movement is the downhill movement of sediment that moves because of gravity.
What are the four types of mass movement?
Rockfall, mudflow, landslide or rotational slips.
What is rockfall?
Bits of rock fall off the cliff fave, usually due to freeze-thaw weathering.
What is mudflow?
Saturated soil (soil filled with water) flows down a slope.
What is landslide?
Large blocks of rock slide downhill
What is a rotational slip?
Saturated soil slump down a curved surface.
What are the four processes of erosion?
Hydraulic action, abrasion, attrition, solution.
What is erosion?
Erosion is the wearing away of rock along the coastline, destructive waves are responsible for erosion on the coastline.
What is hydraulic action?
The sheer power of the waves as they smash against the cliff. Air becomes trapped in the cracks in the rock and causes the rock to break apart.
What is abrasion?
Pebbles grind along a rock platform, much like sandpaper. Over time the rock becomes smooth.
What is attrition?
When rocks that the sea is carrying knock against each other. They break apart to become smaller and more rounded.
What is solution?
The sea water dissolves certain types of rocks. In the UK, chalk and limestone cliffs are prone to this type of erosion.
What are the five stages to wave cut notches/ platforms?
The cliff retreats, weather weakens the cliff, notch increases and cliff collapses, waves cut notch, wave cut platform.
What is transportation?
Sediment carried by the waves along the coastline.
What is the movement of material in waves referred to as?
Longshire drift.
Waves approach the coast at an angle because….
Of the prevailing winds
What is longshire drift?
Waves approach the coast at an angle due to prevailing wind, the swash carries material towards the beach at an angle. The backwash then flows back to the sea, down the slope of the beach. The process repeats itself along the coats in the zig-zag movement.
What are the four types of transportation?
Solution, suspension, saltation and traction.
What is solution?
When minerals in rocks like chalk and limestone are dissolved in sea water and then carried in solution. Not visible.
What is suspension?
Small particles such as silts and clays are suspended in the flow of the water.
What is saltation?
Where small pieces of shingle or large sand grains are bounced along the sea bed.
What is traction?
Where pebbles and larger material are rolled along the sea bed.
What is deposition?
When the sea loses energy, it drops the material is has been carrying. This is deposition.
Deposition can occur on coastlines that have ___________ waves.
Constructive
What are the four factors leading to deposition?
Waves starting to slow down and lose energy.
Shallow water.
Sheltered areas, e.g bays.
Little or no wind.
