EQ2 4.3 A Flashcards
What is the definition of coastal erosion?
Erosion is the process whereby waves (with high energy) strike the coastline and breakdown and remove sediment/material.
What happens to soft rock when hydraulic action and abrasion occurs?
It is forced to go back and form bays and also erode headlands.
Why does discordant coastlines erode at a faster rate of concordant coastlines?
Discordant coastlines erode faster because it is made of hard rock AND soft rock rather then just soft rock (like concordant). Concordant us more resistant so it takes longer to erode.
How are caves formed?
The waves erode the base of the crack through the process of hydraulic action and abrasion.
What is hydraulic action?
The power and force of water and air being forced into cracks in the rock. The pressure increases and expands. Rock chips off and the crack gets bigger.
What is abrasion?
When rocks are picked up by waves and thrown or rubbed against the cliffs. This action wears away the rock and it is gradually removed.
What is attrition?
Rocks that are held within the waves smash into each other. Gradually the rocks become smaller and smoother.
What is the process of creating a cave, arch, stack and stump?
1) Air and water gets into cracks and sediment is thrown into the cliff.
2) a weakness occurs in the headland in the form of a crack or fault.
3) the waves erode the base of the crack through the process of hydraulic action and abrasion. This forms a cave.
4) the cave erodes through to create an arch.
5) the roof of the arch is weathered by chemical and biological processes.
6) the base of the arch is eroded to create a wave cut notch is unsupported and collapses.
7) the arch becomes wider and wider with more erosion and the roof is unsupported. The roof collapses.
8) a stack is formed which is a single standing piece of rock.
9) the base of the stack is eroded creating a wave cut notch. The stack is unstable and will collapse.
10) this leaves a stump which is only visible at low tide.
What is soft rock and hard rock?
Soft rock-soft rock is sedimentary rock which can erode easily. For example clay and sandstone.
Hard rock- hard rock is higher resistant igneous and metamorphic. For example granite.
What are joints?
Joints are smaller cracks found in rocks. They are usually vertical.
What are faults?
Faults are bigger cracks caused by the past tectonic movement where rocks have overlapped.
How are headland formed?
When the sea attacks a section of the coast with alternating bands of hard and soft rock. The bands of soft rock e.g. sand and clay erode more quickly than those of more resistant rock, such as chalk. This leaves a section of land jutting out into the sea called a headland.
What are bays?
The areas where the soft rock has eroded away next to the headland.
How are wave cut platforms formed?
The sea attacks the base of the cliff forming a wave cut notch. The notch increases in size causing the cliff to collapse. The backwash carries the rubble towards the sea forming a wave cut platform.
