Coastal landforms are an important part of Geomorphology in the UPSC syllabus. Questions on features like spits, tombolos, wave-cut platforms, sea caves and stacks have appeared earlier and remain highly relevant due to their conceptual clarity and diagram-based nature.
This blog explains the major coastal landforms formed by sea waves, classified into erosional and depositional features, with examples useful for UPSC answers.
Contents
Coastal Erosional Landforms
1. Wave-Cut Platform
A wave-cut platform is a gently sloping rock surface found between a retreating cliff and the shoreline.
Formation process:
- Sea waves erode the base of a cliff through hydraulic action and abrasion
- A wave-cut notch develops at the base
- Continued erosion causes the cliff to collapse and retreat landward
- The exposed rocky surface becomes a wave-cut platform
Key point for answers:
Wave-cut platforms indicate cliff recession and active marine erosion.
2. Sea Caves, Arches and Stacks
These features represent stages of coastal erosion.
Sequence of formation:
- Cracks on cliffs widen due to hydraulic pressure → Sea caves
- Continued erosion enlarges caves → Sea arches
- Collapse of the arch roof leaves isolated rock pillars → Sea stacks
Examples:
- Sea stacks are common along rocky coasts
- Classic example of canyon analogy: erosion leaving resistant remnants
3. Blow Holes (Natural Chimneys)
Blow holes form when:
- Sea caves extend vertically upward
- Trapped air and water are forced upward during high-energy waves
- Water spurts out like a fountain
Also called: Gloups or natural chimneys
Examples:
- Hummanaya Blowhole, Sri Lanka
- Kiama Blowhole, Australia
4. Coves
Coves are rounded coastal indentations formed where:
- Soft rocks are eroded faster than adjacent hard rocks
- Hydraulic action enlarges weak zones
- Over time, coves may evolve into bays or gulfs
Example:
- Lulworth Cove, Dorset coast (UK)
Coastal Depositional Landforms
5. Bars and Barriers
- Bars are submerged or partially emergent ridges formed by sediment deposition
- They may block river mouths, forming lagoons
- When bars increase in size, they are called barriers
6. Spits and Hooked Spits
- Spits are elongated depositional features extending from the coast into the sea
- Formed due to longshore drift
- When strong waves or storms bend the spit landward, it becomes a hooked spit
UPSC focus:
2019 GS-1 question asked formation of spits and tombolos
7. Tombolo
A tombolo is a depositional feature that:
- Connects an island to the mainland
- Forms in a calm water zone
- Acts like a natural bridge
Indian examples:
- Ratnagiri coast
- Malvan coast (Maharashtra)
8. Looped Bar
When both ends of a depositional bar connect to an island, enclosing a lagoon, it is called a looped bar.
Why Coastal Landforms Matter for UPSC
- High probability 10–15 mark descriptive questions
- Ideal for diagram-based answers
- Links physical geography with dynamic processes
- Relevant for coastal management, erosion and climate change
Conclusion
Coastal landforms showcase the continuous interaction between land and sea. Understanding the process–landform relationship is crucial for both UPSC Prelims and Mains, especially for Geography Optional aspirants.
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FAQs
#WaveCutPlatformUPSC
How are wave-cut platforms formed due to cliff retreat and marine erosion?
#SeaCavesStacksUPSC
Explain the sequential formation of sea caves, arches, and stacks along rocky coasts.
#SpitsAndBarsUPSC
How do spits, hooked spits, bars, and barriers form due to longshore drift?
#TomboloGeomorphology
What is a tombolo and how does it differ from spits and looped bars?
