Waves Revision Notes for Leaving Cert Geography

Waves

Term	Definition
Swash	Water carried up the beach after a wave breaks
Backwash	The water that flows back down the beach to the sea
Shingle	Made up of small rounded pebbles or stones brought ashore by the sea
Marine Deposition	Another way of saying Coastal Deposition
Backshore	The area of a beach that lies above the high tide level. It is reached by waves only during stormy weather
Foreshore	The lower section of the beach next to the water
Storm Beach	Located in the backshore area and mainly consists of stones and gravel

Coastal processes of erosion, deposition and transportation are influenced by the actions of waves
Waves are created by friction between the wind and sea
The size of waves depends on two things:
- Wind Strength: the stronger the wind, the more powerful the wave
- Fetch: The size of the ocean the wind blows over
Large ocean combined with high winds = Stronger waves
When waves reach shallower water at the coast, they break
Waves running up the shore = swash
Waves that run back towards the sea = backwash
Top of the wave = crest
Bottom = trough

Formed when the swash is stronger than the backwash
As the stronger swash runs up the beach, some of the wave soaks into the sand depositing material on the beach
The weaker backwash then returns to the sea
They are low energy waves that are also flat and low, less than 1m high
Constructive waves are most common during summer time

Wave Refraction is when waves bend and change their direction as they approach the shore
As the waves reach the coastline, the headland is encountered first
As they enter shallow water, they begin to slow down near the headland
In deeper water the waves continue at greater speeds
This difference in speed causes the waves to bend inwards around either side of the headland
The erosive power of the wave is concentrated on the headland, so erosion mainly occurs here
It is less powerful when it reaches bays, so deposition occurs