Coastal erosion shapes coastlines into a variety of distinctive landforms. Cliffs, wave cut platforms, caves, arches, stacks, headlands and bays are landforms associated with coastal erosion. These features are created by the relentless action of waves, tides, and weather wearing away the land along the coast.
Here are some of the key landforms shaped by coastal erosion:
Cliffs
Coastal cliffs are steep rock faces formed when the sea erodes the base of the land. Over time, undercutting creates an overhang which eventually collapses, causing the cliff line to retreat inland.
- Formation: Waves erode the foot of the slope, weakening the rock.
- Characteristics: Vertical or near-vertical rock faces overlooking the sea.
Wave-Cut Platforms
As cliffs retreat, a flat area of rock is often left behind at the base of the cliff at sea level. This is known as a wave-cut platform.
- Formation: Abrasion and hydraulic action wear away the rock at the cliff base, leaving a relatively smooth, gently sloping rocky platform.
- Characteristics: Flat, rocky area exposed at low tide, often covered with rock pools.
Caves, Arches, and Stacks
These features often form sequentially in areas with resistant rock, particularly on headlands.
- Caves: Form when waves find weaknesses in the rock face, such as cracks or joints, and erode them inwards.
- Arches: If a cave erodes through a headland, or if two caves on opposite sides of a headland meet, a natural arch is formed.
- Stacks: When the roof of an arch collapses, it leaves an isolated column of rock standing in the sea, known as a stack.
- Formation: Differential erosion exploiting weaknesses in rock.
- Sequence: Cliff -> Cave -> Arch -> Stack -> Stump (eroded stack).
Headlands and Bays
Coastlines made of alternating layers of hard (resistant) and soft (less resistant) rock often develop headlands and bays.
-
Bays: Form where the sea erodes softer rock more quickly, creating sheltered inlets.
-
Headlands: Are left protruding out into the sea where harder rock resists erosion.
-
Formation: Differential erosion rates of varying rock types.
-
Characteristics: Bays are indented, often with beaches; Headlands are exposed, rocky points.
Summary Table of Coastal Erosion Landforms
| Landform | Description | Formation Process(es) |
|---|---|---|
| Cliffs | Steep rock face at the coast. | Undercutting, collapse by wave action. |
| Wave-Cut Platforms | Flat, rocky area at the base of a retreating cliff. | Erosion (abrasion, hydraulic action) at base. |
| Caves | Hollow eroded into a cliff face. | Erosion along lines of weakness. |
| Arches | Natural archway eroded through a headland or stack. | Enlargement of caves meeting or eroding through. |
| Stacks | Isolated column of rock left standing in the sea. | Collapse of a sea arch roof. |
| Headlands | Protruding area of resistant rock into the sea. | Slower erosion of hard rock. |
| Bays | Indented inlet between headlands. | Faster erosion of soft rock. |
These features are dynamic and constantly changing due to ongoing erosional processes.
