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Erosional landforms

The process of erosion can create different landforms along the coastline.

Headlands and bays

Cliffs along the coastline do not erode at the same pace. When a stretch of coastline is formed from different types of rock, headlands and bays can form.

Bands of soft rock such as clay and sand are weaker therefore they can be eroded quickly. This process forms bays. A bay is an inlet of the sea where the land curves inwards, usually with a beach. Hard rock such as chalk is more resistant to the processes of erosion. When the softer rock is eroded inwards, the hard rock sticks out into the sea, forming a headland.

Erosional features such as wave-cut platforms and cliffs can be found on headlands, since they are more open to the waves. Bays are more sheltered with constructive waves which deposit sediment to form a beach.

Waves attack the soft rock between sections of hard rock. This is differential erosion. The coastline changes over time, forming a bay where the erosion takes place, and a headland on either side.

Cliffs and wave-cut platforms

Cliffs are shaped through erosion and weathering. Soft rock erodes quickly and forms gentle sloping cliffs, whereas hard rock is more resistant and forms steep cliffs. A wave-cut platform is a wide gently-sloping surface found at the foot of a cliff.

Sea attacks base. Wave-cut notch forms. Cliff collapses. Wave-cut platform forms. Cliff retreats.

A wave-cut platform is formed when the following occurs:

  1. The sea attacks the base of the cliff between the high and low water mark.
  2. A wave-cut notch is formed by erosional processes such as abrasion and hydraulic action - this is a dent in the cliff usually at the level of high tide.
  3. As the notch increases in size, the cliff becomes unstable and collapses, leading to the retreat of the cliff face.
  4. The backwash carries away the eroded material, leaving a wave-cut platform.
  5. The process repeats. The cliff continues to retreat.

Caves, arches, stacks and stumps

Caves, arches, stacks and stumps are erosional features that are commonly found on a headland.

A crack expands into a cave. A cave expands into an arch. The arch collapses leaving headland and a stack. Wave-cut platform is exposed at low tide. The stack collapses into a stump.
  1. Cracks are widened in the headland through the erosional processes of hydraulic action and abrasion.
  2. As the waves continue to grind away at the crack, it begins to open up to form a cave.
  3. The cave becomes larger and eventually breaks through the headland to form an arch.
  4. The base of the arch continually becomes wider through further erosion, until its roof becomes too heavy and collapses into the sea. This leaves a stack (an isolated column of rock).
  5. The stack is undercut at the base until it collapses to form a stump.