shore platforms - erosion

Question 1

how do shore platforms form?

Answer 1

when destructive waves break repeatedly on steep cliffs in between high and low water level creating a wave-cut notch.
- continued undercutting removes support for the rock strata above it = collapses –> producing steep profile and cliff

Question 2

what happens at the base of the cliff?

Answer 2

at the base of the cliff a gently sloping shore platform is cut into solid rock

Question 3

what happens when platform reaches 500m wide?

Answer 3

friction causes the waves to break on the platform and with no energy reaching the base of the cliff further erosion stops

Question 4

how do weathering processes act on platform?

Answer 4

cold environments = freeze thaw
warm = salt crystallisation

marine organisms eg. algae can accelerate weathering when platform is exposed at low tide –> at night algae release c02 (photoS doesn’t take place at night) –> this mixes with sea water+ makes it more acidic = higher rates of chemical weathering

Question 5

how does abrasion affect shore platforms?

Answer 5

shore platforms are deeply dissected by abrasion as rocks are dragged across the surface by the waves –> where boulders are too large to be removed by the waves they accumulate on the platform

Question 6

at what angle to shore platforms normally slope?

Answer 6

between 0 degrees and 3 degrees as wave erosion can occur anywhere between high and low tide levels

Question 7

explain the process of cliff and shore platforms forming?

Answer 7

• landform of coastal erosion where destructive waves break repeatedly on steeply sloping coastlines
• wave erosion processes such as abrasion, hydraulic action, pounding cause undercutting between the low and high tide levels forming a wave-cut notch
• eg. abrasion occurs when waves armed with rock particles scour the coastline; rock rubbing against rock
• continued undercutting weakens support for the rock strata above the notch, leading to collapse and formation of relatively steep slope/cliff face
• debris removal also ensures that the cliff retreats inland parallel to the coast
• geology (lithology+structure) influences the shape of cliff profile
• sub-aerial processes may influence the profile of the upper part of cliff