The Work of Moving Ice Wind and Sea Waves: Deposition by Sea Waves

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Deposition by Sea Waves

Sea waves help in the deposition of the material eroded from the coastal areas. The larger particles are deposited first, thus they are found near the coast. The finest particles on the other hand, are deposited last and they are deposited generally away from the coast. This selective deposition is sometimes altered by a change in the intensity or force of the waves. Therefore, it is sometimes possible to find very fine particles deposited near the coast where generally larger particles are deposited.

Some of these topographical features formed due to deposition by waves and currents are:

  • Beach: Most of the materials eroded and picked up by the waves are deposited near the coast. Due to the deposition, the sea becomes shallow and a part of the coastal area is raised above the water level. This raised portion is like a flat plain or a platform formed of gravel and sand. This type of depositional features along the coast is termed a beach. The Marina Beach of Chennai and Kovalam Beach of Thiruvananthapuram are the famous beaches of India.

  • Sand Bar: Sometimes the deposits of sand and gravel laid down by waves and currents form embankment, separating the shoreline from the sea. They form barriers between the sea and the mainland. Such deposits are known as sand bars.

  • Spit: When one end of a bar is attached to the coast and the other extends into the sea, it is termed a spit. These spits are formed by the accumulation of materials brought by the waves like sand and gravel.

Formation of a Bar and Tombolo and Spits

Formation of a Bar and Tombolo and Spits

Formation of a Bar and Tombolo and Spits

  • Lagoon: Sometimes due to the 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 known as lagoon.

    • 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.

In brief, it can be said that

  • In areas where the temperature always remains below freezing point, the precipitation occurs in the form of snow. Therefore, these areas are covered with snow. Such regions are called snowfields. Moving ice is called a glacier. They are of two types- continental glaciers and valley glaciers. The major topographical features of glacial erosion are the U-shaped valleys and hanging valleys. The major depositional features of glacial action are the moraines. There are three types of moraines-terminal moraine, lateral moraine, and medial moraine. Topographical features made by glaciers are found in areas of high altitude and high latitude.

  • Action of wind is more effective in arid and semi-arid regions. Wind erodes the rocks, transports the broken material, and deposits it in different areas. Erosional work of wind includes abrasion, attrition and deflation. One of the major topographical features made by wind erosion is mushroom rock. The transportation work of wind is also extensive. The broken particles of rocks are transported to thousands of kilometres. Deposition of the transported material results in formation of the sand dunes and loess.

  • The most important agent shaping coastal landform is wave action. The important works of waves are the breaking up of the rocks, removal of broken material and laying down of this material in different parts of the coastal areas. Erosion by waves is achieved through the processes of abrasion, attrition, hydraulic action, and solution. Erosion by sea waves results in formation of topographical features like sea cliff, sea caves, arches, stacks and stamps. Transportation work of waves makes possible seaward movements of the material accumulated on the coast and coastward movement of the material found in the sea. Depositional work of sea waves is responsible for the formation of bars, spit, beaches, and lagoons.

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