Erosional Landforms
Headland and bay
- Found in areas of alternating bands of resistant (hard) and less resistant (soft) rocks running perpendicular to oncoming waves (discordant coastline)
- Initially, less resistant rock (e.g. clay) is eroded back, forming a bay
- A bay is an inlet of the sea where the land curves inwards, usually with a beach
- The more resistant rock (e.g. limestone) is left protruding out to sea as a headland
Headland and bay formation
Cove
- A cove forms where the coastline has bands of resistant and less resistant rock running parallel to the oncoming waves (concordant coastline)
- There is usually a band of resistant rock facing the oncoming waves, with a band of softer rock behind
- Wave processes of abrasion, corrosion and hydraulic action will exploit faults in the resistant rock and erode through to the softer rock
- Further wave action will erode the softer rock quickly, which will leave behind a circular cove with a narrow entrance to the sea
- Wave refraction within the cove spreads out the erosion in all directions, creating the typical horseshoe shape
- Lulworth Cove in Dorset, UK, is a good example of a cove
The formation of coves
Cliff and wave-cut platform
- Cliffs are shaped through erosion and weathering processes
- Less resistant rock erodes quickly and will form sloping cliff faces
- Steep cliffs are formed where there is harder rock facing the sea
- A wave-cut platform is a wide gently sloped surface found at the foot of a cliff:
- As the sea attacks the base of a cliff between the high and low water mark, a wave-cut notch is formed
- Abrasion, corrosion and hydraulic action further extend the notch back into the cliff
- The undercutting of the cliff leads to instability and collapse of the cliff
- The backwash of the waves, carries away the eroded material, leaving behind a wave-cut platform
- The process repeats and the cliff continues to retreat, leading to a coastal retreat
The formation of cliffs and wave-cut platforms
Cave, arch, stack and stump
- Found on a headland due to wave action and sub-aerial weathering
- Any weaknesses in the headland are exploited by erosional processes of hydraulic action, abrasion and corrosion
- As the crack begins to widen, abrasion will begin to wear away at the forming cave
- The cave will become larger and eventually break through the headland to form an arch
- The base of the arch continually becomes wider and thinner through erosion below and weathering from above
- Eventually, the roof of the arch collapses, leaving behind an isolated column of rock called a stack
- The stack is undercut at the base by wave action and sub-aerial weathering above until it collapses to form a stump
Stack formation