Coastal features Flashcards
What’s the formation of a headland and bay
These are formed on discordant coastlines where bands of hard and soft rock sit at right angles to the sea.
The soft rock is eroded faster by waves approaching the shore and the hard rock is siting out into the sea, known as headlands
These are eroded by abrasion and hydraulic action and solution
The area between the headlands are known as bays and is in an area of sheltered rock
- bays are formed from the rapid erosion of restraint rock
An example of this is Dorset coast
Whats long shore drift
process of longshore drift.
Swash is where waves, driven by prevailing wind push material up the
beach at an angle
the returning backwash is dragged back by gravity down the beach at
right angles.
Whats the formation of a sand spit
A sand spit is formed by the process of longshore drift
Swash is where waves, driven by prevailing wind push material up the
beach at an angle
the returning backwash is dragged back by gravity down the beach at
right angles.
spits form when there is a change in direction on a coastline allowing a sheltered area for deposition
material slowly builds up to appear above the water
the spit develops as long as the supply of deposits is greater than the amount of
erosion
the shape can become hooked or curved at the end in response to changes in
wind direction/currents
a salt marsh may form in a sheltered area behind a sand spit
an example is Spurn Head.
What’s hydraulic action
- hydraulic action — pounding waves compress trapped air in the rocks creating an explosive blast which weakens and loosens rock fragments (2 P marks)
Abrasion
- abrasion/corrasion — rock fragments thrown against the headland breaking down the cliff face, wearing away the rock (2 P marks)
Solution
- solution/corrosion — carbonic acid/salts in sea
water dissolves rock (2 P marks)
Whats the formation of a cave
Cracks at the base of the headland within the inter-tidal zone become exposed through hydraulic action —
pounding waves compress trapped air in the rocks creating an explosive blast which weakens and loosens rock fragments (2 P marks)
-cracks are further widened by weathering processes such as salt crystalisation
Expand on abrasion and solution etc
-overtime the crack develops and become wave cut notches. Further processes of abrasion deepen the notch to form caves
-as a result of wave refraction, which distorts the wave direction, waves concentrate their energy on the sides, this deepens the cave
Ano example of this would be tilly whim caves
Whats the formation of an arch
Cracks at the base of the headland within the inter-tidal zone become exposed through hydraulic action —
pounding waves compress trapped air in the rocks creating an explosive blast which weakens and loosens rock fragments (2 P marks)
-cracks are further widened by weathering processes such as salt crystalisation
Expand on abrasion and solution etc
-overtime the crack develops and become wave cut notches. Further processes of abrasion deepen the notch to form caves
-as a result of wave refraction, which distorts the wave direction, waves concentrate their energy on the sides, this deepens the cave
-wave refraction effects all three sides of the headland. If two caves are are aligned the waves may cut through to form an arch. Wave cut notches widen the base of the arch
-vertical joint in the roof of the arch are exposed by tall breakers, joints can also be weathered by carbonation of limestones, with blowholes forming
-durdle door
Whats the formation of a stack
Cracks at the base of the headland within the inter-tidal zone become exposed through hydraulic action —
pounding waves compress trapped air in the rocks creating an explosive blast which weakens and loosens rock fragments (2 P marks)
-cracks are further widened by weathering processes such as salt crystalisation
Expand on abrasion and solution etc
-overtime the crack develops and become wave cut notches. Further processes of abrasion deepen the notch to form caves
-as a result of wave refraction, which distorts the wave direction, waves concentrate their energy on the sides, this deepens the cave
-wave refraction effects all three sides of the headland. If two caves are are aligned the waves may cut through to form an arch. Wave cut notches widen the base of the arch
-vertical joint in the roof of the arch are exposed by tall breakers, joints can also be weathered by carbonation of limestones, with blowholes forming
-overtime the arch becomes unstable and collapses under its own weight and gravity to form a pillar of rocks called a stack.
The stack is further eroded at its base creating new wave cut notches
Old harry along Dorset coast
Wave cut platforms
With wave cuts at its maximum, the waves undercut the foot of the cliff to form a wave cut notch
Over a period of time thr notch enlarges till the cliff above it is left unsupported and collapses under its own weight and gravity
Material from the eroded cliff can then be used to further erode it. As this process is repeated, the cliff retreats
Kimmeridge Ledges
Tombolo is formed by the process of longshore drift
Swash is where waves, driven by prevailing wind push material up the
beach at an angle
the returning backwash is dragged back by gravity down the beach at
right angles.
Tombolo form when there is a change in direction on a coastline allowing a sheltered area for deposition
material slowly builds up to appear above the water
tombolo develops as long as the supply of deposits is greater than the amount of
erosion
The spit is grown out from the mainland and joined to an island creating a tombolo
Eg Chelsie beach
Formation of a bar
A sand spit is formed by the process of longshore drift
Swash is where waves, driven by prevailing wind push material up the
beach at an angle
the returning backwash is dragged back by gravity down the beach at
right angles.
spits form when there is a change in direction on a coastline allowing a sheltered area for deposition
material slowly builds up to appear above the water
the spit develops as long as the supply of deposits is greater than the amount of
erosion
A bar is formed as a spit grows across a bay joining up two headlands
Eg Chesil beach
