Depositional landforms of sea waves
Important depositional landforms of sea waves are sea beaches, bars, barriers, splits, offshore, etc.
Beaches and Dunes
Beaches are characteristic of shorelines that are dominated by deposition but may occur as patches along even the rugged shores. Most of the sediment making up the beaches comes from land carried by the streams and rivers or from wave erosion.
Beaches are temporary features. The sandy beach which appears so permanent may be reduced to a very narrow strip of coarse pebbles in some other season. Most of the beaches are made up of sand-sized materials. Beaches are called shingle beaches that contain excessively small pebbles and even cobbles.
Just behind the beach, the sands lifted and winnowed from over the beach surfaces will be deposited as sand dunes. Sand dunes forming long ridges parallel to the coastline are very common along low sedimentary coasts.
Bars, Barriers and Spits
A ridge of sand and shingle formed in the sea in the off-shore zone (from the position of low tide waterline to seaward) lying approximately parallel to the coast is called an off-shore bar.
An off-shore bar that is exposed due to the further addition of sand is termed a barrier bar. The off-shore bars and barriers are commonly from across the mouth of a river or at the entrance of a bay. Sometimes such barrier bars get keyed up to one end of the bay when they are called spits.
Spits may also develop attached to headlands/hills. The barriers, bars, and spits at the mouth of the bay gradually extend leaving only a small opening of the bay into the sea and the bay will eventually develop into a lagoon.
The lagoons get filled up gradually by sediment coming from the land or from the beach itself (aided by wind) and abroad and wide coastal plain may develop replacing a lagoon. Do you know, the coastal off-shore bars offer the first buffer or defence against storms or tsunamis by absorbing most of their destructive force.
Then come to the barriers, beaches, beach dunes, and mangroves, if any, to absorb the destructive force of the storm and tsunami waves. So, if we do anything which disturbs the ‘sediment budget’ and the mangroves along the coast, these coastal forms will get eroded away leaving human habitations to bear the first strike of the storm and tsunami waves.
This article covers the topic ‘Depositional landforms of sea waves‘ for Upsc.