3.1.3.2 Systems and processes Flashcards
Outline the sources of sediment
- rivers (90%)
- cliff erosion (5%)
- offshore bars (5%)
Define tides
The periodic rise and fall of the ocean surface
Define currents
Permanent or seasonal movement of surface water
What are the 3 types of currents?
- longshore drift
- rip currents
- upwelling
Define a spring tide
When the earth, sun and moon align and the highest tidal ranges are produced
Define a neap tide
When the earth, sun and moon are at right angles and the lowest tidal ranges are produced
Wave height of a constructive wave
Less than 1m
Wavelength of a constructive wave
Up to 100m
Wave period of a constructive wave
8-10 seconds
Define wave period
Time taken for a wave to travel one wavelength
Wave frequency of a constructive wave
6-9 per minute
Define wave frequency
Amount of waves passing a single point per minute
What is the wave movement of a constructive wave
Elliptical
What is the swash and backwash of a constructive wave
- strong swash
- weak backwash
What is the impact of constructive waves on the beach profile
Gentle slopes
What is the wave frequency of destructive waves
11-15 per minute
What is the wave movement of a destructive wave
Circular
What is the swash and backwash of a destructive wave
- weak swash
- strong backwash
What is the wavelength of a destructive wave
20m
What is the height of a destructive wave
Over 1m
What is the wave period of a destructive wave
5-6 seconds
How many sediment cells are in UK and Wales
11
Define a sediment cell
Closed system, defined stretches of coastline which maintain the majority of sediment, defined by prominent physical features.
What are the 5 main ways to erode a coastline
- abrasion
- hydraulic action
- quarrying
- solution
- attrition
Define abrasion
Rocks transported by the water smashing against the cliffs
Define hydraulic action
Air in cracks is compressed when waves crash in. This pressure breaks off the rock.
Define quarrying
The force of the wave against the rock
Define solution
Soluble rocks being dissolved
Define attrition
Bits of rock smash against each other in the water and break into smaller parts.
Factors effecting rate of erosion
- width of beach
- fetch of the waves
- type of rock in the cliffs
Define lithology
Chemical composition of the rock
