Coastal landforms

• Figure 2 shows an individual component which is a wave-cut notch at Flamborough head this is the start of the process of a wave-cut platform being formed.
• Waves break against the foot of the cliff with erosion concentrated at the high tide mark.
• This creates a wave cut notch like the one in figure 2.
• Rock begins to overhang and becomes unstable and eventually collapses.
• Over time, the cliff retreats leaving a wave-cut platform.
• Wave-cut platforms are never usually longer than few hundred meters as waves break before the cliff dissipating energy reducing the rate of erosion and limiting growth of the platform.
• Figure 3 shows a diagram of how wave-cut platforms are formed with the wave-cut notch at the high tide mark and the cliff retreating due to the overhanging rock collapsing.
• The coastal system acts as an input to the system and the wave-cut platform acts as a temporary store of the sediment.
• Figure 4 shows an example of a wave-cut platform in East Sussex.
• This can only be seen at times of low tide and clearly illustrates the gentle gradient of the wave-cut platform in contrast with the steepness of the cliff.
• Sedimentary rocks can dip steeply causing steep vertical cliffs like in Figure 5.
• Absence of a beach: due to long fetch which encourages erosion
• Gentle cliffs: weak rocks which are prone to slumping
• A sheltered location has low energy waves and a short fetch which results in a build-up of debris and a lower overall cliff angle
• Wide beaches absorb wave energy
• Rate of retreat depends on marine factors like fetch, wave energy and presence of a beach
• Also sub-aerial factors like geology
• Rapidly retreating cliffs usually have weak rock like glacial Till cliffs at the Holderness Coastline
• Other factors include: rising sea levels and human activities
• Figure 6 shows how the different factors affect the rate of retreat with weathering and mass movement as these make rocks prone to erosion thus increasing rate of retreat and wave energy being determined by strong prevailing winds and a long fetch increases the rate of retreat.
• Coastal morphology is related to rock type and lithology (physical characteristics)
• Strata: layers of rock
• Bedding planes: breaks in strata caused by gaps in rock formation
• Joints: vertical fractures caused by contraction as sediment dries or earth movements
• Folds: pressure during tectonic activity
• Faults: formed when stress exceeds internal strength of the rock
• Dip: angle which the strata lie
• Caves, Arches, Stacks and Stumps
• Waves erode joints and faults making caves.
• If overlying rock collapses a blowhole will form.
• Arches: two caves joining or one cave eroding through the headland
• This gap can be enlarged by weathering.