Sea Waves

Waves are the undulations formed on the surface of water bodies like river, sea and ocean. Sea waves are formed by the friction of air on the sea water.

Components of sea waves are crest, trough, etc.

Waves move because wind pushes the water body in its course, while gravity pulls the crests of the waves downward.

The wave breaks when the depth of the water is less than half the wavelength of the wave. Three types of breaking waves are plunge, swash, and backwash.

Sea-coast is a part of the land, which faces the sea. Sea-shore is a part of land, which is in close contact with sea. Shore is divided into three zones-back shore, fore-shore and off-shore.

Sea waves are the effective agent of gradation on coast and shore. Three types of functions are performed by the sea waves- erosion, transportation, and deposition.

Waves operate as an agent of erosion in four ways. These are hydraulic action, abrasion, attrition, and solution.

Significant coastal features are formed due to marine erosion by sea waves. The erosional landforms are sea cliff, wave cut platform, sea caves, blow holes, inlets, coves and headland, marine arches, stack and stump.

Sea cliff has a steep slope facing the sea. Waves break at the foot of the cliff.

Wave cut platforms are the platforms occurring at elevations above the average height of waves.

Caves generally develop at the base of the cliffs.

Blowhole is a vertical tunnel that is formed when erosion extends upto the cliff top.

Inlets are formed when the roof of the cave collapses.

Waves erode the softer rock to form sea coves.

Harder rocks remain as narrow projections called headlands.

When two caves on opposite side meet, sea arch is formed.

Sea stack is an isolated column, which is caused when the arch falls due to continued erosion.

Due to continuous erosion of stack, upper portion of stack collapses and forms sea stumps.

Eroded materials are transported by sea waves in different manner. Materials involved in the transportation by sea waves include sands, gravels, silts, pebbles, cobbles, shells, etc.

Depositional features are beach, sandbars, spit, lagoon and dunes.

Beaches are formed by the deposition of sand, gravel and, pebbles.

The narrow, elongated deposits of sand and gravel that built up on the sea floor parallel to the coastline are called sandbars.

Sand spits are narrow, elongated ridges of sand.

The partially enclosed salt water lake is called lagoon.

Dunes are formed by the sand deposited by sea waves along the coast.

Coastline is the boundary between the coast and the shore.

Two types of coastlines are submerged coastlines and coastlines of emergence

Submerged coastlines are of two types submerged upland coasts, and submerged lowland coasts.

Different types of submerged coastlines are the Fiord coastline, the Ria coastline, the Dalmatian coast and the Haff coast.

Coastlines of emergence are formed either by an uplift of the land or by lowering of the level of the sea.

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