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Coastal Landforms: Coastal Landforms are formed where the land meets the sea. A Coastal Landform is formed by both marine and terrestrial processes. There are various types of coastal landforms produced by these processes, which either cause erosion or deposition. The type of rock that these processes are acting on, the amount of energy in the system, sea currents, waves, and tides are just a few of the variables that affect how the coastal landscape is formed.
Coastal Landforms Meaning
Considering that changes in the morphology of many coasts can be observed on an annual (or shorter) period, coastal processes are among the most active geologic processes. The shape of the land and sea floors, in addition to wave activity, affects coastal landforms. Whether the coast is moving forward (emerging) toward the sea or backward (submerging) toward the land.
The Action of Sea Water
- Sea waves and tsunamis are the most powerful agents of marine erosion.
- Currents are relatively less impactful means of erosion but are important means of transportation.
- Tides are mainly agents of deposition.
Formation of Sea Waves
Sea waves are undulations of seawater. The waves are caused by friction between the water and the blowing wind. As the wind blows, it transfers its energy through friction, causing the water to move in a circular motion. As the wave nears the shore, the friction of these circular waves with the seafloor causes the wave base to slow down. The top of the wave curves over until the wave crashes and breaks on the shore. Finally, the water recedes into the sea.
Anatomy of a Sea Wave
Here is the anatomy of a sea wave:
- Crest: The upper part of the wave is called the crest.
- Trough: The lower part of the wave is called the trough.
- Swash: It is the forwarding movement of seawater upon a beach after the ‘breaking of a wave’ Backwash: It is the receding movement of seawater after the ‘breaking of a wave
Types of Waves
There are two Types of Waves:
- Constructive Waves: These waves gently roll over the coasts and help deposition on the coast.
- Destructive waves: These waves roll over the coast with tremendous force and erode coastal rocks.
Coastlines and Shores
- Seashore: The zone of land immediately adjacent to the sea.
- Shoreline: The line of demarcation between the land and the sea.
- Coast: The part of land adjoining the sea.
- Coastline: The boundary between the coast and the shore.
Various Coasts Diagram
Below is the diagram of various Types of Coasts:
Marine Erosion Processes
- Abrasion: When the waves strike against the coast with eroded materials
- Attrition: when coarse sands and pebbles collide with each other during transport and break down into finer particles.
- Solvent Action: The process of dissolving coastal rocks.
- Hydraulic Action: The splashing action of sea waves against the rocks.
Coastal Landforms Types
There are mainly two types of Coastal Landforms i.e. Erosional Coastal Landforms and Depositional Coastal Landforms.
Coastal Landforms Erosional
- Chasms: Chasms are narrow and deep indents on the coastline. They are formed when on the sea-facing side, hard and soh rocks occur in alternative bands.
- Bay: The wave action wears away the soft rocks forming indents. The chasm widens till it forms a bay.
- Capes: The hard rocks which are left in the project as capes in the seawater.
- Sea cliffs: A steep rocky coast rising almost vertically above the seawater is called a sea cliff.
- Wave-cut Platforms: When Sea waves strike a cliff continuously, the cliff gradually retreats over time. A rock-cut flat surface is formed in front of the cliff, called a wave-cut platform.
- Cave: Sea caves are formed at the base of a cliff. Sea waves erode softer rocks at the base quickly creating holes or hollows. These hollows over time enlarge to form sea caves.
- Arch: It is formed when two caves develop on either side of projected rock and ultimately unite.
- Stack: When the roof of the arch collapses and the end sides remain standing, a pillar-like structure on the coast is formed. It is called a stack.
- Stump: When the stack is eroded further, the height of the stack is reduced to form a stump.
- Blow-hole/Gloup: Continued action of sea waves makes holes in the cave roof. This hole is called a Gloup or blow hole.
- Geo: With further erosion, the blowholes enlarge and the roof collapses. A long, narrow inlet called Geo is developed.
Coastal Landforms Erosional Diagram
Coastal Landforms Depositional
- Beaches: These are deposits of marine sediments consisting of sand, shingles, cobbles etc on the seashore.
- Spits and bars: A spit is a low-lying ridge of sands and pebbles with one end connected to the mainland and the other end terminating into the sea.
- Hook: A bent spit is called a hook.
- Bar: It is a ridge of sand lying parallel to the coast. They are submerged features.
- Tombolo: When a bar extends and joins an island to the mainland or joins two islands, it is called a tombolo. For example, the Chesil beach in Dorset, England connects the Isle of Portland with the mainland.
- Lagoons: The enclosed area of seawater between a bar and the coast is called a lagoon. For example Chilka lake on the Odisha coast and Pulicat lake on the Andhra coast.
Coastal Landforms Depositional Diagram
Below is the diagram for Coastal Depositional Landforms:
Coastal Landforms FAQs
Q) What is a Coast?
Ans. A coast is any area of land that borders the water. Where the land meets the water is where the coast begins or ends; this is referred to as the coastline. The waves, tides, and currents partly shape these coastlines. The basic composition of the land and water significantly impacts how the coasts are formed.
Q) What is a beach?
Ans. These are deposits of marine sediments consisting of sand, shingles, cobbles etc on the seashore.
Q) What is a hook?
Ans. A bent spit is called a hook.
Q) What are Cliffs?
Ans. Cliffs are a formation’s highest peak or summit. Cliffs typically develop as a result of the weathering and erosion of the rocks. Natural occurrences like wind or rain that shatter the bits of rock cause weathering. Strong winds and large waves in coastal places separate the softer or grainier rocks from the firmer rocks. Cliffs are the more rigid rocks that are still present.
Q) What is Rock Debris?
Ans. Massive rocks that have been destroyed by a melting glacier are left as dispersed remains known as rock debris.
Other Indian Geography Topics
Other Fundamental Geography Topics