A rocky headland exposed to persistent marine wave action undergoes sequential destructive geomorphic processes over time. Arrange the following coastal features in the correct chronological order of their evolution, starting from the earliest stage of headland erosion to the final remnant landform.
- 1Hydraulic action and wave abrasion enlarge sea-level joints into a wave-cut notch and cave.
- 2Continuous wave erosion pierces completely through the headland, forming a sea arch.
- 3Subaerial weathering and gravity cause the unsupported roof of the arch to collapse.
- 4An isolated, vertical column of resistant rock remains standing as a sea stack.
- 5Basal wave undercutting weakens the vertical pillar, causing it to collapse into a sea stump.
Answer
The correct sequence of coastal landform evolution is: (1) Hydraulic action and wave abrasion enlarge sea-level joints into a wave-cut notch and cave, (2) Continuous wave erosion pierces completely through the headland, forming a sea arch, (3) Subaerial weathering and gravity cause the unsupported roof of the arch to collapse, (4) An isolated, vertical column of resistant rock remains standing as a sea stack, and (5) Basal wave undercutting weakens the vertical pillar, causing it to collapse into a sea stump.
Coastal headland degradation follows a strict geomorphic sequence driven by wave action and weathering. Initially, marine processes (hydraulic action and abrasion) enlarge lines of weakness into a cave. As erosion cuts through the headland, an open arch is created. Subaerial weathering then weakens the arch roof until it collapses under gravity, leaving an isolated pillar called a stack. Persistent wave undercutting at the base eventually causes the stack to fall, leaving behind a low-lying stump.
Step-by-Step Solution
Key Concept
Sequential Headland Erosion and Coastal Geomorphology