Geography – Arid environments | e-Consult

I will describe the formation of a cliff, a prominent coastal landform. Cliffs are formed through the relentless action of wave erosion.

Processes Involved:

• Hydraulic Action: The force of waves crashing against the cliff face compresses air in cracks and crevices. This pressure can widen the cracks and eventually dislodge rock.
• Abrasion (Corrasion): Waves carry sediment (sand, pebbles, boulders) which are hurled against the cliff face, acting like sandpaper and wearing away the rock.
• Attrition: As rocks are carried by waves, they collide with each other, breaking down into smaller and smoother fragments. This reduces the size of the sediment and contributes to the erosive power of the waves.
• Solution (Corrosion): Some rocks, like chalk and limestone, are soluble in seawater. The seawater dissolves the rock, creating caves and weakening the cliff face.

Factors Influencing Development:

• Rock Type: Cliffs are more likely to form in areas with resistant rock types like granite or sandstone. Softer rocks like clay or shale will erode more quickly, resulting in gentler slopes.
• Wave Energy: Areas exposed to high wave energy, such as those facing open sea, will experience faster cliff erosion. Sheltered bays will have less erosion.
• Coastal Geology: The type of rock underlying the cliff influences its stability. Faults and weaknesses in the rock can accelerate cliff erosion.
• Sea Level Change: Rising sea levels can increase the rate of cliff erosion by exposing more of the cliff face to wave attack. Falling sea levels can expose previously submerged areas to weathering and erosion.

The continuous erosion of the base of the cliff undercuts the overlying rock. Eventually, the overhanging rock becomes unstable and collapses, leading to cliff retreat. This process is often accelerated by weathering, which weakens the rock and makes it more susceptible to erosion. The fallen material accumulates at the base of the cliff, forming a wave-cut platform.