CAPF AC 2021 Q83: Geography – Physical Geography & Geomorphology
Caves, arches, stacks and stumps are the landscape features of which one of the following?
- (a) River
- (b) Wave
- (c) Limestone
- (d) Wind
Answer: (b) Wave
Explanation
Landforms made by sea waves
How to think: these four features come in a sequence on a rocky coast.
Waves attack a headland and wear it away step by step.
| Step | Feature | How it forms |
|---|---|---|
| 1 | Sea cave | Waves hollow out a crack in the cliff |
| 2 | Sea arch | Caves on both sides of a headland meet |
| 3 | Stack | The roof of the arch collapses, leaving a pillar |
| 4 | Stump | The stack is worn down to a low rock |
Features of the other agents:
| Agent | Typical features |
|---|---|
| River | V-shaped valley, waterfall, meander, delta |
| Limestone (karst) | Sinkhole, stalactite, stalagmite, cavern |
| Wind | Mushroom rock, sand dune, loess |
Answer: (b) Wave.
Why each option is right or wrong
- (a) Incorrect. A river makes valleys, waterfalls, meanders and deltas.
- (b) CORRECT. Sea waves carve caves, arches, stacks and stumps on a coast.
- (c) Incorrect. Limestone areas have caves too, but with sinkholes and stalactites, not stacks.
- (d) Incorrect. Wind makes mushroom rocks and sand dunes in deserts.
Key point
Wave erosion sequence: cave → arch → stack → stump. Other coastal features: cliff, wave-cut platform (erosion); beach, bar, spit, lagoon (deposition).
Remember
Cave → arch → stack → stump: work of sea waves.
Common mistakes
- Marking limestone because caves are also found in karst regions.
- Mixing up a stack (sea pillar) with a stalagmite (cave pillar).
- Forgetting that the four features form one after another on a headland.
Exam tip
Educated guess: the word stack is used only for a rock pillar standing in the sea. That one word decides the answer.
Sources
- NCERT Class VII Geography — Our Changing Earth (work of sea waves)
- NCERT Class XI Geography — Fundamentals of Physical Geography, Chapter 7: Landforms and their Evolution (coastal landforms)