caves, arches, stacks and stumps
---> A stump is formed by the the action of the sea and weathering.
---> The sea erodes a crack with hydraulic action. This is when water hits the cliff compressing air in cracks. As the water retreats the pressure is released breaking off pieces of rock.
---> This makes the crack bigger forming a cave. It if is a headland, caves will form on either side. Eventually the backs of the caves meet and an arch is formed. In time the arch will collapse forming a stack.
---> This is due to undercutting of the sea. Corrasion is what happens, which is when rocks in the sea are thrown against the cliff breaking off pieces of the cliff.
---> The arch becomes wider at the bottom and is unable to support the weight above. Eventually the arch is pulled down by gravity.
---> Weathering is also active on the cliff face and further weakens the cliff. Through time the sea erodes the bottom of the stack and it collapses to leave a stump, which is coveed by the sea at high tide.
Headland and bays
- only occur on coastlines where soft and hard rocks are found at right angles to the sea.
- the soft rock erodes more quickly than the hard rock forming bays
- the hard rock is more resistant and sticks out as headlands
- there should also be reference to the processes of erosion