Topic 2 - Erosional landforms

Question 1

How do wave -cut platforms form?

Answer 1

• When waves break against the foot of a cliff, erosion tends to be concentrated close to the high-tide line, this creates a wave-cut notch, as the notch gets bigger, the cliff is undercut and the rock face above becomes unstable, eventually collapsing
• As these processes repeat, the notch migrates inland and the cliff retreats, leaving behind a gently sloping wave-cut platform-this is normally only completely exposed at low-tide

Question 2

What is rate of retreat?

Answer 2

When the cliff becomes unstable and collapses, leading to the retreat of the cliff face

Question 3

What factors affect the cliff profile and its rate of retreat?

Answer 3

• Steep cliffs tend to occur where the rock is strong and resistant to erosion, such as igneous and metamorphic rocks
• Sedimentary rocks that are dipping steeply or even vertically tend to produce steep and dramatic cliffs
• The absence of the beach and presence of a long fetch and high energy waves will further encourage this through rapid erosion and undercutting
• Gentle cliffs reflect weak or unconsolidated rocks that are prone to slumping, rocks that are dipping towards the sea also tend to have low-angle cliffs
• A sheltered location with low-energy waves and a short fetch will result in subaerial debris building building up at the flood of the cliff, reducing its overall angle-a wide beach will absorb more wave energy and prevent significant undercutting and steepening
• The rate of retreat of a cliff face very much depends on the balance marine factors and terrestrial factors
• The most rapidly retreating cliffs tend to be composed of very weak rocks