Bays, Headlands, and Wave-Cut Platforms
Coastal landscapes are shaped by the interaction of waves with different rock types, creating distinctive features such as bays, headlands, and wave-cut platforms.
Bays and Headlands Formation
Bays and headlands form along coastlines with alternating bands of hard and soft rock. The process involves:
- Waves eroding the coastline through hydraulic action and attrition.
- Soft rock erodes faster, creating bays.
- Hard rock resists erosion, forming headlands that stick out to sea.
- During calm periods, sheltered bays allow for deposition, forming beaches.
Highlight: The differential erosion of hard and soft rock is key to the formation of bays and headlands.
Wave-Cut Platforms
Wave-cut platforms are flat areas of rock formed at the base of cliffs. Their formation process includes:
- Waves form a wave-cut notch at the cliff base through undercutting.
- As the notch grows larger, the cliff eventually collapses due to lack of support.
- The process of undercutting and collapse repeats, causing the cliff to retreat and increase in height.
- A wave-cut platform is exposed at low tide as the cliff continues to retreat.
Vocabulary: Wave-cut notch - An indentation formed at the base of a cliff by wave erosion.
Caves, Arches, Stacks, and Stumps
These features form through the continued erosion of headlands:
- Waves enter faults or cracks in the headland, eroding through hydraulic action and abrasion.
- A cave forms and widens due to marine erosion and sub-aerial processes.
- The cave may erode through the headland, creating an arch.
- The arch widens until it collapses, leaving a stack.
- Continued erosion at the base of the stack leads to its collapse, forming a stump.
Example: The formation sequence of caves, arches, stacks, and stumps can be observed in many coastal areas, such as the Old Harry Rocks in Dorset, England.