Waves

Waves are created by the transfer of energy from the wind blowing over the surface of the sea. However, tsunamis are the result from submarine shock waves generated by the earthquake or volcanic activity. As the strength of the wind increase, so too does frictional drag and size of the waves. The energy required by the waves depends upon three factors:

Wave Formation

When wind turbulences blow across water, the produce

Types of Waves

The steepness of waves determines whet5her they are likely to build up or degrade a beach. There are two extreme forms:

       They often have a short fetch. They approach the shore slowly. The swash is greater than the backwash. There is a gap of 7 to 10 seconds between each wave crest breaking.

        They have a long fetch and are built up by strong winds. The backwash is greater than the swash. These waves break more frequently than constructive waves. 

Wave Refraction

Where waves approach an irregular coastline they are refracted, i.e. they become increasingly parallel to that coastline. This is best illustrated where a headland separates two bays. It has already been seen that a wave approaching the shore loses velocity as the depth of water decreases. As the sea bad usually shelves more rapidly off a headland than in a bay, the wave loses velocity more quickly there. The orthogonals represent four stages in the advance of a particular wave. It is apparent from the convergence of lines S¹, S², S³, S ⁴, That the wave energy becomes concentrated upon, and so accentuates erosion at, the headland.

Wave erosion

   There are four main processes by which the sea can erode the land. These are similar to those of river.

        This is the force or compression of air and water within the wave. This forces the rocks apart along lines of weakness. Blocks or fragments of rook break away.

        This is the wearing down of the rocks by the load. The load is either moved along the sea floor or carried in the waves.

        This is the wearing down of the load itself by friction as the waves move. Rounded pebbles and sand are produced.

        This is chemical erosion. It involves both the chemical change and disintegration of some minerals when they come into contact with sea water.