Waves and currents contribute to erosion and deposition processes. The erosion of the sea depends on the size and strength of the waves, the slope, the height of the shore between high and low tides, the shape of the shore, the composition of the rocks, the depth of the water, human activity, etc. This article explains the erosional landforms of waves and currents such as chasms, wave-cut platforms, sea cliffs, sea caves, sea arches, and hanging valleys which is an important part of the geomorphology syllabus for the UPSC IAS Exam.

Erosional Landforms of Sea Waves and Currents

• Ma­rine erosion by sea waves and other currents, as well as solution processes, results in significant coastal landforms.
• Cliffs, caves, caverns, indented shoreline, stacks, chimneys, arch, inlets, wave-cut platforms, and so on are all part of it.

Marine Erosional Landforms

Chasms

• Chasms (a deep dip or notch on the edge or surface of anything) are narrow, deep indentations.
• They are formed by the action of waves through vertical planes of weakness in the rocks, resulting in headward erosion (downcutting).
• Further, the headward erosion is hampered over time by lateral erosion of the chasm mouth, which widens until a bay is formed.

Wave-Cut Platform

• The narrow flat region frequently found at the base of a sea cliff or along the shoreline of a lake, bay, or sea that was generated by erosion is known as a wave-cut platform, shore platform, coastal bench, or wave-cut cliff.
• Wave-cut platforms are most noticeable at low tide when they appear as vast expanses of a flat rock.
• The landward side of the platform is sometimes covered in sand, forming a beach, and the platform is only visible during low tides or when storms shift the sand.
• Wave-cut platforms are formed when damaging waves strike the cliff face, generating an undercut between the high and low watermarks due to abrasion, corrosion, and hydraulic action, resulting in a wave-cut notch. This notch eventually expands into a cave.
• The waves erode this section until the cave's ceiling falls as a result of the pressure and freeze-thaw or biological weathering acting on it, causing the cliff to withdraw landward.
• Attrition breaks down the fallen material into tiny pieces, forming the wave-cut platform at the cave's foot, while some cliff debris may be washed into the sea.
• This may be deposited at the platform's end, creating an off-shore beach.

Sea Cliffs

• Sea cliffs are the most common erosional seashore landform.
• Cliffs are formed by exceptionally steep rock faces that are adjacent to the coast.
• Almost all sea cliffs are steep, with heights ranging from a few meters to 30 meters or more.
• Their steepness is due to wave-induced erosion near sea level and subsequent rock collapse at a higher elevation.
• The sea makes a notch at the base of the cliff, progressively eroding the bluff until it falls.
• The English Channel's Chalk Cliffs and Dover's White Cliffs are the most well-known cliffs.

Sea Arches

• When two caves meet on the opposite side of a cliff and join together, they produce a bridge-like structure known as an arch.
• The entrance of these archways might be arcuate or rectangular, with the opening reaching below the water level.
• An arch can reach heights of tens of meters above sea level.
• Sea arches commonly occur when waves assault a rock from two opposing directions, a process known as differential erosion.
• The Needle Eye, in Wick, Scotland, is an example.

Sea Caves

• Long-term wave attacks against the cliff's base, as well as rock debris blasted against the cliff by lashing waves, generate holes in vulnerable areas, which then enlarge and deepen to form sea caves.
• England's Flamborough Head is an example.

Hanging Valleys

• The rivers appear to be hanging over the sea if the fluvial erosion of a stream at the beach does not match the retreat of the sea. Hanging valleys are the name given to these river valleys.
• The shapes of valleys, such as U-shaped and V-shaped valleys, are used to classify them.
• Hanging Valleys can always be found in the shape of a U. It is actually due to their peculiar positioning and structure above their main valleys.
• Apart from that, they also have a steep wall characteristic at the point where both the valleys meet.
• The hanging valleys have ruptures and cracks which are formed naturally. It is seen that rivers usually flow through that path from the mountains.

Significance of Waves and Currents

• Wave has high energy potential.
• They are a reliable source of energy that is less dependent on fossil fuels.
• Ocean currents play a significant role in climate management by transporting heat from the equator to the poles.
• The importance of ocean currents to sea life cannot be overstated.
• They transport nutrients and food to creatures that are firmly linked to a single location, as well as reproductive cells and ocean life to new locations.

Conclusion

The erosional and depositional processes are carried on by sea waves, which are aided by winds, currents, tides, and storms. The majority of the changes along the beaches are caused by waves. The constant impact of breaking waves has a significant impact on the coasts. Tides and currents make very little direct attack on the coastline when they come into contact with it. The nature of rocks, the amount of rock exposed to the sea, the impact of tides and currents, and human meddling all influence the rate of marine erosion.

FAQs

MCQs

1. Which landform is created when wave erosion cuts away the base of a coastal cliff?

A) Sand dune
B) Sea cliff
C) Delta
D) Lagoon

2. What is the name of the flat, bench-like structure formed at the base of sea cliffs due to wave erosion?

A) Spit
B) Barrier island
C) Wave-cut platform
D) Estuary

3. How are sea arches formed?

A) By glacial movement
B) By the deposition of sediments
C) By wave erosion on weak coastal rocks
D) By volcanic activity

4. What feature is formed when a sea arch collapses?

A) Sea cliff
B) Spit
C) Sea stack
D) Wave-cut platform

5. Which of the following best describes a hanging valley?

A) A valley with a river at its base
B) A smaller valley elevated above the main valley
C) A deep sea trench
D) A mountain pass

GS Mains Questions and Model Answers

Q1: Discuss the formation and significance of erosional landforms created by wave action along coastlines.

Answer: Erosional landforms created by wave action include sea cliffs, wave-cut platforms, sea caves, sea arches, and sea stacks. These structures form as waves continuously impact coastal rocks, eroding and reshaping the landscape. Sea cliffs result from the erosion of rock faces by powerful waves, creating steep vertical formations. Wave-cut platforms develop as waves erode the base of a cliff, leaving behind a flat surface. Sea caves form when waves carve hollows into weaker sections of rock, which may evolve into sea arches if they break through to the other side. When a sea arch collapses, a sea stack is left standing as an isolated pillar. These landforms not only highlight the dynamic processes at work in shaping coastlines but also contribute to coastal biodiversity and are significant in studying erosion patterns and environmental changes.

Q2: Explain the processes involved in the formation of wave-cut platforms and their ecological importance.

Answer: Wave-cut platforms are formed through the erosion of sea cliffs by continuous wave action. As waves hit the base of a cliff, they erode the rock, leading to the collapse of the cliff face over time. The debris is then carried away by the water, leaving behind a flat, bench-like structure known as a wave-cut platform. These platforms are significant because they provide insight into historical sea levels and erosion rates. Ecologically, wave-cut platforms host a variety of marine organisms, including barnacles, algae, and mollusks, contributing to the coastal ecosystem's biodiversity. They also act as natural barriers, dissipating wave energy and reducing the impact on inland areas, thus playing a role in coastal protection.

Q3: Assess the impact of erosional landforms on coastal management and human activity.

Answer: Erosional landforms, such as sea cliffs, wave-cut platforms, and sea arches, have significant implications for coastal management and human activity. While these landforms can be visually stunning and attract tourism, they pose challenges for coastal development due to their unstable nature and susceptibility to further erosion. Sea cliffs, for example, may experience sudden collapses that threaten infrastructure and safety. Coastal management strategies must account for the natural erosion processes, implementing measures such as buffer zones and managed retreat to prevent damage. Understanding these landforms aids in the planning of sustainable coastal development and helps protect communities from erosion-related hazards. Additionally, preserving these natural features is essential for maintaining ecological balance and supporting marine biodiversity.

Previous Year Questions on Erosional Landforms

1. UPSC CSE Prelims 2021:

Question: Which of the following is an example of an erosional landform caused by wave action?

A) Delta
B) Sea stack
C) Lagoon
D) Spit

Answer: (B)

Explanation: A sea stack is an example of an erosional landform created by wave action. It forms when a sea arch collapses, leaving behind an isolated rock pillar.

2. UPSC CSE Mains 2019 (GS Paper 1):

Question: "Examine the processes that lead to the formation of various coastal erosional landforms and discuss their significance in coastal geography."

Answer: Coastal erosional landforms such as sea cliffs, wave-cut platforms, sea caves, and sea arches are formed through the continuous action of waves eroding the coast. The processes involved include hydraulic action, where water force impacts the rock, and abrasion, where rock fragments carried by waves wear away the coastline. Over time, these processes result in distinctive features like sea caves, which may develop into arches and eventually collapse to form sea stacks. These landforms are significant as they provide insights into the geological history and dynamics of coastal regions. They help in understanding erosion rates, past sea levels, and the influence of climate change on coastal processes. Additionally, they support marine habitats and contribute to the natural beauty that attracts tourism, which can be essential for local economies.