Coasts As Natural Systems Flashcards
What are the characteristics of constructive waves?
- adds material to the coast
- low wave width with long wave length
- strong swash
What are the characteristics of destructive waves?
- removes material
- causes cliff face erosion
- tall in relation to length
- strong backwash
- formed by distant weather systems
What are tides?
They are the periodic rise and fall of the sea caused by the gravitational pull of the sun and moon
What is the difference between spring and neap tides?
Spring tides are high because the moon is opposite the sun so it has forces acting on it from both directions. Neap tides are lower as the moon is not aligned.
What is the difference between high and low energy coasts?
High energy: - rocky coastline - cliffs and headlands - e.g. in Cornwall Low energy: - less powerful waves - beaches and spits - sheltered areas, sandy
What is a sediment cell?
A stretch of coastline within which sediment movement is more or less contained. They contain inputs, transfers and stores of sediment.
What are the sources of sediment?
- rivers
- cliff erosion
- offshore sediment
- wind
How does wave energy change at headlands and bays?
Wave energy is concentrated at headlands but dissipated in the bay
What is the positive feedback in weathering?
If the rate of debris removal is greater than the rate of weathering and mass movement, positive feedback occurs as the rate of weathering and mass movement increases.
What is the negative feedback of weathering?
If debris removal is slow and ineffective, it will lead to a build up of debris that protects the cliff face. (Negative feedback)Weathering and mass movement will decrease.
What are the three types of weathering?
Biological - plants and animals
Chemical - involves a chemical reaction causing erosion
Mechanical/ physical - break up of rocks without any chemical changes occurring
What are the types of mass movement?
Soil creep - extremely slow, wet Mudflow - flow, quite rapid, went Run off - flow, rapid, dry Landslide - slide, rapid, dry and wet Rockfall - fall, rapid, dry
What is wave quarrying?
A braking wave traps air as it hits the cliff. The air is compressed into gaps causing huge pressure. As the water retreats there is an explosive effect of the air being released.
