Which of the following options represents the correct sequential order of physical stages involved in the landward retreat of a rocky cliff and the formation of a wave-cut platform?
- 1Concentrated marine erosion, mainly hydraulic action and abrasion, attacks the base of the cliff between high and low tide marks.
- 2Persistent undercutting along the cliff foot leads to the excavation of a wave-cut notch.
- 3The weight of the unsupported overhanging rock exceeds its tensile strength, causing it to collapse under gravity.
- 4Repeated cliff collapse causes the cliff face to recede landward, exposing a gently sloping bedrock terrace known as a wave-cut platform.
Answer
The correct sequence of stages in cliff retreat and wave-cut platform formation begins with concentrated wave erosion attacking the cliff base between tide marks, followed by the development of a basal wave-cut notch, the subsequent gravitational collapse of the unsupported overhang, and ultimately the landward retreat of the cliff face leaving an exposed wave-cut platform.
Cliff retreat begins when concentrated wave action (hydraulic force and abrasion) attacks the cliff base in the intertidal zone. Persistent undercutting carves a horizontal recess called a wave-cut notch. As erosion deepens the notch, the overhanging rock face loses structural support and eventually collapses under gravity. Over extended periods, this cycle of undercutting, overhang collapse, and cliff recession leaves behind a wide, gently sloping bedrock terrace termed a wave-cut platform.
Step-by-Step Solution
Key Concept
Coastal Cliff Retreat and Wave-Cut Platform Formation