Coasts Flashcards
Define Fetch
The distance the wind is blowing over water creating waves. Bigger fetch = bigger waves
What are the two different types of waves and how do they differ?
Destructive:
* Erosion - takes away coastline
* Large waves AKA plunging waves -> they plunge onto shore
* Backwash stronger than swash
Constructive:
* Deposition - builds features
* Small waves AKA spilling waves -> they spill onto shore
* Backwash is weaker than swash
How many constructive waves are there per minute?
6-8
How many destructive waves are there per minute?
10-14
What shape are constructive waves?
Flat
What shape are destructive waves?
Plunging
What season are constructive waves most prevalent?
Summer
What season are destructive waves most prevalent?
Winter/spring
Define swash
Water coming up onto beach/coast after the wave breaks
Define backwash
Water retreating back down the beach after a wave has broken
How many high and low tides are there daily?
Two high tides and two low tides
Name some erosional features of coastlines
- Bay and headland
- Cliff
- Wave cut platform
- Cave
- Sea Arch
- Sea Stack
- Sea stump
- Blowhole
- Geo
Name some depositional features of coastlines
- Beach
- Sandspit
- Sand bar
- Tombolo
- Lagoon
Define prevailing wind
The wind that occurs most frequently in an area
What is the fetch like on the west coast of Ireland and why?
It is large forming very powerful waves. This is because there is 5000km of open sea between the west coast and the USA
What is the prevailing wind in Ireland?
South west
What is the fetch on the east coast of Ireland like and why?
It is small so waves don’t have the same power because there is only 100km of open sea to Wales.
Define wave frequency
The number of waves passing a given point per second. High wave frequency means more energy delivered to coastline
Explain wave refraction
The bending of waves as they approach a coastline at an angle. This occurs because waves slow down in shallower water, causing them to align more parallel to the shore.
Define tide
The periodic rise and fall of sea levels due to the gravitational pull of the moon and sun
Define constructive waves
Low energy waves that deposit material onto the shore forming beaches. Strong swash and weak backwash
Define destructive waves
High energy waves that erode the coastline. They have a weak swash and strong backwash, removing material from the shore.
Define longshore drift
The movement of sediment along the coast due to waves hitting the shore at an angle
Define coastal erosion
The wearing away of land by natural forces such as waves, wind and rain