Geo 2026: Erosional coastal landforms

Where bands of hard and soft rock meet the coast at right angles (a discordant coastline), differential erosion happens.
The soft rock (such as clay) erodes quickly, forming bays. The hard rock (such as chalk or limestone) erodes slowly, sticking out as headlands.
Once formed, headlands are exposed to stronger waves (wave refraction), while bays become sheltered and collect beaches.

Waves attack the foot of a cliff between high and low tide by hydraulic action and abrasion.
This cuts a wave-cut notch.
The rock above is left unsupported (overhanging) and eventually collapses.
The cliff retreats inland. Repeated over time, this leaves a gently sloping, rocky wave-cut platform, exposed at low tide.

On a headland, waves exploit a crack or joint by hydraulic action and abrasion.
The crack widens into a cave.
The cave is eroded right through the headland to form an arch.
The roof of the arch is weakened by erosion below and weathering above, and collapses, leaving a stack.
The stack is eroded at its base and collapses to form a stump, covered at high tide.
In the exam: use 'because', 'therefore' and 'leading to', name the processes, and draw a labelled sequence diagram.

The hardest idea is differential erosion: different rocks erode at different speeds.
Picture a coastline where bands of hard rock (such as chalk or limestone) and soft rock (such as clay) meet the sea at right angles. This is a discordant coastline.
The waves attack all of it, but the soft rock erodes quickly and is cut back into bays. The hard rock erodes slowly, so it is left sticking out as headlands.
Once the shape forms, it changes how waves behave. Waves bend (refract) around the headlands, so their energy is concentrated on the headlands and spread out in the bays. Therefore bays become sheltered, so deposition happens and beaches form there.
The headlands keep taking a battering, which is why caves, arches, stacks and stumps form on headlands. Example: Swanage Bay in Dorset is cut into softer rock between harder chalk and limestone headlands, and Old Harry Rocks is a chalk stack.

Getting the sequence wrong: it is always crack, cave, arch, stack, stump.
Not naming processes: say hydraulic action and abrasion widen the crack, and weathering weakens the arch roof.
Thinking bays form from hard rock: bays form in soft rock; headlands are hard rock.
Putting the wave-cut notch at the top of the cliff: it forms at the foot, between high and low tide.
Unlabelled diagrams: label each stage and the processes, and number them in order.

Your class TIF slide shows a map of the coast around Swanage, Dorset, with a key: clay and sands (soft), chalk (hard) and limestone (hard).
From north to south:
Studland Bay: soft sands and clays, eroded back into a bay.
Ballard Point: a headland of hard chalk.
Swanage Bay: soft clays and sands, eroded into a bay.
Durlston Head: a headland of hard limestone.
This is differential erosion on a discordant coast: the bands of rock meet the sea at right angles, so soft bands become bays and hard bands stay as headlands. Old Harry Rocks, a chalk stack, stands at the end of the chalk headland.

In a photograph, look for:
Cliff: a steep rock face. Wave-cut notch: an undercut groove at the base of the cliff. Wave-cut platform: flat, rocky area at the cliff foot, seen at low tide.
Headland: land sticking out into the sea. Bay: a curved inlet, often with a beach.
Cave: a hollow in the cliff. Arch: a gap right through a headland. Stack: a pillar of rock separated from the headland. Stump: a low rock, covered at high tide.
In a labelled diagram: draw a sequence of numbered sketches (crack, cave, arch, stack, stump), add arrows for wave attack, label the processes (hydraulic action, abrasion, weathering), and show high and low tide lines for notches and platforms. Labels should explain, not just name.