4.3 A - Geology - Distinctive Coastal Landscapes Flashcards
What is the rock type like on a concordant coastline?
The concordant coastline is made up of just hard rock/igneous or metamorphic like limestone
What features are found on a concordant coastline?
Small coves and caves are created on concordant coastline as the rock is so hard less erosion takes place
What is the rock type like on a discordant coast?
Alternating bands/strata of hard and soft rock
What features are found on a discordant coast?
The soft rock is eroded quickly to make bays and the hard rock creates headlands. Arches, stacks and stumps are also found
What is an example of both?
Lulworth cove is a small cove on a concordant coastline. Ballard point and Swanage bay are a headland and a bay on a discordant coastline
What are joints and faults? How do they affect erosion?
Joints are small cracks in rock created through large amounts of pressure and weathering on the rock. Faultlines are the result of tectonic plates moving towards or away from each other. Both make the rock weaker and more vunerable
What is the difference between hard/soft rock? With examples
Hard rock such as limestone or chalk is stronger and more resistant and less permeable. Soft rock such as clay is the opposite
Describe what are the characteristics of headlands and bays?
Headlands will have steep sides due to the powerful waves hitting them first. Bays often have large beaches and are further back than headlands
Explain the stages in the formation of headlands and bays?
On the discordant coastline, the alternating bands of hard and soft rock are hit by powerful destructive waves that have come from far away so have fetch and the soft rock is eroded faster than the hard rock so is starts to create cleare convergences and divergences. These keep being eroded backwards creating bays and the hard rock sticking out becomes headlands
Describe what are the characteristics of wave cut platforms?
Large wide flat platform from cliff retreat
Smooth due to abrasion from debris of cliff
Overhang and wave cut notch
Explain the stages in wave cut platforms formation?
Destructive waves hit the headlands first so they have lots of energy. They start to erode a wave cut notch where the cliff meets the sea. Once this has been eroded a lot, the rock above becomes unstable, collapses and is dragged out to sea. This repeats
What are the characteristics of arch/stack/stumps?
They are made on headlands that usually have cracks. Waves crash into it and increase cracks by abrasion and hydraulic action. This keeps going until a cave is formed and then until the cave is broken through all the way to make an arch. Rock supporting arch is pushed laterally and worn away until arch collapses crating a stack. This is eroded at the base to form a stump
Explain how stumps are formed?
When an arch becomes unstable the top collapses creating an isolated stack. This is top heavy and erodes vertically downwards until a low stump is formed
