Coastal Processes Flashcards
Wave types
Constructive and destructive
What is a constructive wave
strong swash and weak backwash.
the strong swash brings sediments to build up the beach.
the backwash is not strong enough to remove the sediment.
the waves are low and further apart.
Destructive wave features
weak swash and strong backwash.
the strong backwash removes sediment from the beach.
the waves are steep and close together.
What is the ‘fetch’
How far a wave has travelled
Types of mass movement
Rockfall
Mudflow
Landslide
Rotational slip
What is rockfall
Bits of rock fall off the cliff face
What is mudslide
Saturated soil (soil filled with water) flows down a slope
What is a landslide
Large blocks of rock slide downhill
What is rotational slip
Saturated soil slumps down a curved surface
Types of erosion:
Hydraulic action
Abrasion
Attrition
Solution
What is hydraulic action
The sheer power of the waves smashes against the cliff, air gets trapped into the cracks of the rocks and then the rocks break apart
What is abrasion
When pebbles grind across the rock platform like sand paper and become smooth
What is attrition
When rocks in the sea knock against each other, they break apart become smaller and more rounded
What is solution
When the sea water that is slightly acidic dissolves certain tyoes of rocks like chalk and limestone cliffs
What is Deposition
When the sea loses energy and it drops the material that it has been carrying
Why does ‘deposition’ happen
Waves slow down and lose energy
Shallow water
Sheltered areas (bays)
Litte or no wind
What is a wave cut platform
A wave-cut platform, shore platform, coastal bench, or wave-cut cliff is the narrow flat area often found at the base of a sea cliff or along the shoreline of a lake, bay, or sea that was created by erosion
How are wave cut platforms formed
1) sea attacks base if the cliff
2) wave cut notch is formed by erosion (hydraulic action and abrasion)
3) as the notch increases in size the cliff becomes unstable and collapses
4) backwash carries away the eroded material, leaving a wave-cut platform
5) proccess repeats
Crack ——-> Stump Formation
1) Cracks are widened in the headland by hydraulic action and abrasion
2) As the waves continue to slam against the cracks it begins to open up a cave
3) The cave becomes larger and eventually breaks through the headland to form an arch
4) the base of the arch continually becomes wider, until its roof collapses this leaves a stack
5) The stack is undercut at the base until it collapses to form a stump
What are ‘spits’
A spit is an extended stretch of beach material that projects out to sea and is joined to the mainland at one end. Spits are formed where the prevailing wind blows at an angle to the coastline, resulting in longshore drift
How are spits formed
1) Sediment is carried by longshore drift.
2) When there is a change in the shape of the coastline, deposition occurs. A long thin ridge of material is deposited. This is the spit.
3) A hooked end can form if there is a change in wind direction.
Waves cannot get past a spit, therefore the water behind a spit is very sheltered. Silts are deposited here to form salt marshes or mud flats.
