Landforms - How they form and their characteristics Flashcards
How are headlands and bays formed
Cliffs along the coastline do not erode at the same pace. When a stretch of coastline is formed from different types of rock, headlands and bays can form.
Bands of soft rock such as clay and sand are weaker therefore they can be eroded quickly. This process forms bays. A bay is an inlet of the sea where the land curves inwards, usually with a beach. Hard rock such as chalk is more resistant to the processes of erosion. When the softer rock is eroded inwards, the hard rock sticks out into the sea, forming a headland
How are cliffs and wave cut platforms formed
A wave-cut platform is formed when the following occurs:
1) The sea attacks the base of the cliff between the high and low water mark.
2) A wave-cut notch is formed by erosional processes such as abrasion and hydraulic action - this is a dent in the cliff usually at the level of high tide.
3) As the notch increases in size, the cliff becomes unstable and collapses, leading to the retreat of the cliff face.
4) The backwash carries away the eroded material, leaving a wave-cut
5) platform.
The process repeats. The cliff continues to retreat.
Caves, arches, stacks and stumps
1) Cracks are widened in the headland through the erosional processes of hydraulic action and abrasion.
2) As the waves continue to grind away at the crack, it begins to open up to form 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 through further erosion, until its roof becomes too heavy and collapses into the sea. This leaves a stack (an isolated column of rock).
5) The stack is undercut at the base until it collapses to form a stump.
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How are Beaches formed
Beaches are made up from eroded material that has been transported from elsewhere and then deposited by the sea. For this to occur, waves must have limited energy, so beaches often form in sheltered areas like bays. Constructive waves build up beaches as they have a strong swash and a weak backwash
Sandy beaches are usually found in bays where the water is shallow and the waves have less energy. Pebble beaches often form where cliffs are being eroded, and where there are higher energy waves.
How are Spits and bars formed
This is how spits are 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.
4) 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.
Sometimes a spit can grow across a bay, and joins two headlands together. This landform is known as a bar
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