Systems and processes Flashcards
Name some factors which affect wave energy:
- Strength of the wind
- Duration of the wind
- Fetch
Describe tides
Changes in the water level of the sea/ocean caused by the gravitational pull of the moon.
Define tidal range
Difference between high and low tides
Define rip currents
Strong localised underwater currents
How are rip currents formed?
When a series of plunging waves caused a build-up of water at the top of the beach. The backwash is forced below the surface.
Give some landforms found in high-energy environments
Headlands
Cliffs
Wave-cut platforms
Rocky coasts
High-energy environments are found:
- Along stretches of the Atlantic-facing coast; powerful waves all year
- Where the rate of erosion exceeds the rate of deposition
Give some landforms found in low-energy environments
Beaches
Spits
Sandy coasts
Low-energy environments are found:
- Along stretches of the coast where the waves are less powerful
- Where the rate of deposition exceeds the rate of erosion
Name some sediment sources:
Rivers Cliff erosion longshore drift Wind Glaciers
What is a sediment cell?
A stretch of coastline where the movement of sediment is contained.
Give an example of an input, transfer and store in a sediment cell:
Input - Costal erosion
Transfer - Longshore drift
Store - Sand dunes
Define sediment budgets
Material in a sediment cell
What does the sediment budget aim to do?
Maintain a state of dynamic equilibrium; erosion and deposition balanced.
Describe the types of mechanical weathering
- Freeze-thaw: water enters cracks in rock, freezes and expands putting pressure on the rock and causing it to break off
- Wetting and drying: rocks expand when they get wet and contract as they dry, causing them to crack
- Salt crystallisation: water evaporates leaving salt crystals behind, these can grow overtime exerting pressure on the rock
Describe the types of biological weathering
- Plant roots (seaweed) grow through small cracks, widening these as they grow
- Bird and animals burrowing
- Algae secrete chemicals, promoting solution
Describe the types of chemical weathering
- Carbonation: rainwater absorbs carbon dioxide, forming a weak acid which reacts with calcium carbonate in rocks
- Oxidation: reaction of rocks with oxygen, leaving them vulnerable to more weathering
- Solution: dissolving of rock minerals
Describe the process of mass movement
The downhill movement of material under the influence of gravity
Give some examples of mass movement
Mudflows
Landslide
Rockfall
Soil creep
Describe the types of costal erosion:
- Hydraulic action: sheer force of water entering cracks in the rock
- Corrasion/Abrasion: sediment hurled at the cliff face/ dragged along the cliff
- Solution: weak acids dissolve alkaline rock
Describe the types of costal transportation processes:
- Traction: rolling of sediment along the seabed which is too heavy to be carried by the sea
- Saltation: sediment bounces along the seabed, light enough to be lifted but not carried
- Suspension: lighter sediment picked up and carried within the flow of water
What factors effect the type of transpiration seen at a costal environment?
Velocity (energy)
Particle size
Describe the process of longshore drift:
Waves approach the beach at an angle, carrying material up the beach. The backwash pulls the sediment vertically down (perpendicular to the beach front). This results in a zigzag movement of sediment along the beach.
Describe the process of costal deposition:
Deposition occurs when the velocity of the water can no longer transport particles of a certain size.
Describe the process of deposition in a high-energy environment:
Clay and sand is transported away leaving behind larger, coarser pebbles to form a shingle beach.
Describe the process of deposition in a low-energy environment:
Small clay particles will drop to the seabed to form mudflats.
What is upwelling?
Cold water from deep in the ocean moves towards the surface
What factors effect the rate of erosion at a coastline?
Rock type
Beaches - absorb wave energy
Weathering and mass movement - weakening cliff and producing rock fragments
Waves - time of year
