What Are Marine Depositional Landforms?
Just like rivers deposit sand and rocks, the sea also deposits materials (sand, pebbles, and rock debris) when waves and currents slow down. This creates different coastal landforms over time.
1️⃣ Beach – The Shoreline of Sand and Pebbles
- When waves bring sand and small rocks and deposit them on the coast, a beach is formed.
- This is a temporary landform because strong waves can wash away the sand.
- Example: Goa Beaches (India), Miami Beach (USA).
2️⃣ Bar – A Submerged Sandbank in the Sea
- Sometimes, waves and tides deposit sand and pebbles under the water, forming a long ridge away from the shore.
- This remains underwater and is called a bar.
- The water trapped between the bar and the coast forms a lagoon (a shallow waterbody).
- Example: Chilika Lake (India), Pulicat Lake (India) (both are lagoons formed due to bars).
3️⃣ Barrier – A Bar That Stays Above Water
- If a bar rises above water, it is called a barrier.
- It acts like a natural wall, protecting the land from strong waves.
- Example: Outer Banks (USA), Barrier Islands of Florida.
4️⃣ Tombolo – A Sand Bridge Connecting an Island
- When sand and pebbles connect an island to the mainland, it's called a tombolo.
- It looks like a natural bridge of sand.
- Example: St. Michael’s Mount (UK), Adam’s Bridge (India-Sri Lanka).
5️⃣ Shoal – A Hidden Underwater Ridge
- A shoal is a submerged ridge made of sand or rocks just below the water surface.
- It is dangerous for ships because they can hit it and get stuck.
- Example: Dogger Bank (North Sea), Great Bahama Bank.
6️⃣ Spit and Hook – A Narrow Sand Projection into the Sea
- A spit is a long narrow strip of sand that extends from the land into the sea, but one end is still attached to the mainland.
- If the tip of the spit bends inward (towards the coast), it is called a hook.
- Example: Spurn Head (UK), Dhanushkodi Spit (India).
7️⃣ Reef – Natural Coral or Rock Structures in the Sea
- A reef is a ridge of coral or rock just beneath or above the sea surface.
- The Great Barrier Reef in Australia is the largest coral reef in the world (2,300 km long!).
- Coral reefs are important because they protect coasts from erosion and support marine life.
- Example: Lakshadweep Reefs (India), Maldives Reefs.
🌟 Summary (Easy Way to Remember!)
- Beach – Sand on the coast.
- Bar – A sandbank under the sea, forming lagoons.
- Barrier – A bar that stays above water.
- Tombolo – A sand bridge connecting an island.
- Shoal – A hidden underwater ridge (dangerous for ships).
- Spit & Hook – A narrow sand extension into the sea (hook has a curved tip).
- Reef – A natural rock or coral formation in the sea.
