coastal landscapes produced by marine processes (2B.4C)

Question 1

wave cut notches and platforms

Answer 1

wave cut notch= a curved indentation of about 1-2 m high extending along the base of a cliff: it forms between the high tide and low tide marks, where destructive waves break against the cliff.

• it begins to undercut the cliff. as it gets bigger through hydraulic action and abrasion, the rock above becomes unstable. eventually the upper part of the cliff collapses
• this process repeats and therefore the notch migrates inland and the position of the cliff retreats leaving behind a wave cut platform.

wave cut platform= flat rock surface exposed at low tide, extending out to sea from the base of a cliff.
- rock just below low tide level is always submerged, it’s uneroded as it’s never exposed to wave impact.
- so it is left as flat rock surface, the wave cut platform.
! however ! weathering attacking weaknesses in the platform surface may produce indentations, creating rock pools at low tide.

Question 2

cliffs

Answer 2

steep slopes that are usually unvegetated.

• marine erosion of land between the high tide and low tide mark by hydraulic action and abrasion forms a wave cut notch
• the notch deepens until the overlying rock collapses by mass movement due to the force of gravity.
• the exposed face forms a cliff.

Question 3

cave- arch- stack- stump sequence

Answer 3

1. cracks at base of headland widened due to hydraulic action as air becomes pressured forcing crack to widen. they are then further widened through weathering processes and abrasion until the initial notch is deepened forming a cave.
2. wave refraction leads destructive waves concentrating energy of the sides deepening the cave. it affects all 3 sides. if 2 caves are aligned, the waves may cut through to form an arch. wave cut notches widen the base of the arch.
3. over time the arch becomes unstable because of this and collapses under its own weight to form a pillar of rick called a stack (EG Old Harry along the Dorset Coast) this stack is eroded through marine processes creating wave cut notches at its base and also through sub- aerial processes which weaken the stack from above)
4. exposed stack will collapse forming a stump. this material is further eroded through attrition and transported away to be deposited within the bay.