As geomorphological agents, sea waves and currents erode the ma­rine features, forming significant coastal landforms. The Coastal Landforms are shaped by the constant motion of the waves, tides, and currents. Currents are created when waves are refracted while entering shallow water. These longshore currents carry along with themselves vast quantities of material and sediments. Waves and currents also erode sediments from cliffs and shorelines and transport them onto beaches. This article will explain the topic “Waves and Currents as Geomorphological Agent ” in detail which will be quite useful for individuals taking the UPSC Exam.

Waves and Currents as Geomorphological Agents

Waves

• When waves break, the water is propelled with considerable force onto the shore, and sediments on the seabed are churned up at the same time.
• Storm and tsunami waves, unlike conventional breaking waves, can have far-reaching effects in a short period of time.
• On calm days with mild winds, waves cause little damage to the shoreline and can even assist in the formation of beaches and other depositional features.

Erosional Landforms Due to Waves

Cliffs, Terraces, Caves, Stacks, and Stumps

• On the high rocky beaches, cliffs are abundant.
• There may be a level or slightly sloping platform at the base of such cliffs, covered in rock debris from the sea wall behind.
• A wave-cut terrace is defined as a platform that is higher than the typical height of waves.
• Erosion will not be uniform when the upper section of a coastal rock is firm and the lower part is soft.
• The lowest component of the structure erodes quickly, resulting in the emergence of a hollow section.
• This hollow section gradually develops into a sea cave as a result of repeated wave movement.
• Sea arches are generated in the same way as land arches.
• The isolated standing boulders in the water that was previously a component of the cliff are known as sea stacks.
• These stacks have the appearance of little islands in the sea.
• Stumps are small underwater stacks of rocks.

Depositional Landforms Due to Waves

Beaches and Dunes

• Beaches are the features of shorelines where deposition is the dominant factor.
• Beaches are made out of sand-sized components that are only present for a short time.
• Shingle Beaches are defined as beaches with an abundance of small pebbles and even cobbles.
• Sand dunes form as long ridges parallel to the coastline right behind the beaches.

Bars, Spits, and Lagoons

• Waves and currents deposit sand and gravel on the beach, creating bars that separate the shoreline from the sea.
• Between the mainland and the sea, they serve as a barrier.
• A spit is formed when one end of such a bar is attached to the coast and the other stretches into the sea.
• A tombolo is a type of deposition landform in which an island is connected to the mainland by a small spit or bar.
• Both ends of the bar occasionally combine to enclose a section of seawater between the coast and the bar due to wave and current deposition.
• The confined area of the sea becomes a saline lake known as the Lagoon.
• In most cases, a lagoon is connected to the sea via a short strait.
• Lagoon Lakes include Chilka and Pulicat Lakes.

Depositional Landforms due to Waves

Currents

• Tides and currents make very little direct attack on the coastline when they come into contact with it.
• Tides primarily affect maritime erosion by extending an erosion line into an erosion zone.
• This zone corresponds to the area between the low water level and the high water level.
• Currents help to move eroded debris and deposit it as silt, sand, and gravel along the coasts.

Wave As A Geomorphological Agent

Other Factors Affecting Coastal Landforms

• Other than the action of waves, the coastal landforms depend upon:
  • the configuration of land and seafloor
  • whether the coast is advancing (emerging) seaward or retreating (submerging) landward.

To change the coastal landscape, marine erosion agents act in the following ways:

Corrosion

• Corrosion is a mechanical erosion process.
• Waves laden with rock debris crash on cliff walls, slowly eroding them.
• Currents and tides wash the eroded material into the sea, completing the task.

Attrition

• When waves contact with loose particles of rock detritus such as boulders, pebbles, shingles, and fine sand, attrition occurs.
• These materials are broken down into finer, smaller, and rounder particles as a result of attrition, which is largely responsible for the fine sand that makes up the beaches.
• Waves crashing against the rocks can get into the joints and fissures.
• The trapped air inside is crushed right away.
• The compressed air expands with explosive violence as the waves recede.
• As a result of the recurring movement, the fissures widen and rock fragments are pulled away.

Hydraulic Action

• Hydraulic action refers to the erosion that occurs when water moves against a rock on the surface, causing mechanical weathering.
• It is the ability to dislodge and transport rock fragments by moving water (flowing or waves).
• Other types of water-facilitated erosion, such as static erosion, in which water leaches salts and floats off organic material from unconsolidated sediments, and chemical erosion, also known as chemical weathering, are distinct from hydraulic action.
• It is a mechanical process in which a river's flowing water rushes against its banks and bed, eliminating rock particles.

Solvent Action

• This is a term used to describe the chemical erosion of rocks.
• Only limestone beaches are affected by this process.
• On limestone coasts, seawater's solvent impact on calcium carbonate causes chemical changes in the rocks, resulting in disintegration.

Conclusion

Waves aided by winds, currents, tides, and storms contribute to erosion and deposition processes. The rate of ocean erosion depends on the nature of the rock, the amount of rock exposed to the sea, the influence of tidal and tidal currents, and human activity. Coastal terrain is formed as a result of the constant action of waves, tides, and currents.