Deposition by Sea Waves
Sea waves are helpful in the deposition of the material eroded from the coastal areas.
Oceanic currents are also helpful in deposition of the transported material.
The larger particles are deposited first therefore they are found near the coast.
On the other hand, the finest particles are deposited last and they are deposited generally away from the coast.
This selective deposition is sometimes altered or affected by a change in the intensity or force of the waves.
Thus it is sometimes possible to find very fine particles deposited near the coast where generally larger particles are deposited.
A number of topographical features are formed due to deposition by waves and currents.
Some of these topographical features are discussed here:
Most of the material eroded and picked up by the waves is deposited near the coast.
Due to this deposition, the sea becomes shallow and a part of the coastal area is raised above the water level.
This raised portion is almost like a flat plain of a platform formed of gravel and sand.
This type of depositional features along the coast is called a beach.
Marina Beach of Chennai and Kovalam Beach of Thiruvananthapuram are the famous beaches of India.
Sometimes the deposits of sand and gravel laid down by waves and currents form embankment, separating shoreline from the sea.
They thus form barriers between the sea and the mainland.
Such deposits are called sand bars.
They sometime pose difficulties in navigating.
When one end of a bar is attached to the coast and other extends into the sea, it is called a spit.
These spits are formed by the accumulation of materials brought by waves like sand and gravel.
Sometimes due to deposition of waves and currents both the ends of the bar join to enclose a part of the sea water between the coast and the bar.
This enclosed part of the sea forms a lake of saline water.
This saline water lake is called a lagoon.
Sometimes the lagoons are formed due to wave erosion also. A lagoon is generally connected with the sea through a narrow passage.
The Chilka and Pulicate lakes on the north-eastern coast and lake Vembanad on Kerala coast are examples of lagoon lakes in India.