Chapter 3 - Coastal Systems & Landscapes - Complete Flashcards
What are the 5 inputs into the coastal system? t wf sc w w
- Tides
- Wave refraction
- Sea currents
- Waves
- Wind
What are the 2 outputs from the coastal system?
- Sediment removal
- Energy
What are the 4 processes in the coastal system? E L W C
- Erosional landforms
- Longshore drift
- Waves
- Coast
What are the 2 stores in the coastal system?
- Beach (Landscape)
- Deposition
What are the 4 factors which keep beaches in dynamic equilibrium?
- The supply of sand.
- The energy of the waves.
- Changes in the sea- level.
- The location of the shoreline.
What is the sand supply in dynamic equilibrium?
Input and output of sand into the beach must be equal.
Sand is food for beaches and gives shorelines protection from waves.
Being starved of sand can cause higher rates of erosion.
What is the waves in dynamic equilibrium?
The erosion action of a wave is greatest when the wave is high. The angle at which they strike a beach and how much sand they are carrying can also influence the rate of erosion.
Define the 4 causes of sea level change?
- Eustatic
- Isostatic
- Tectonic plate activity
- Thermal expansion (50% responsible)
What is the location of the shoreline in dynamic equilibrium?
Shorelines move back and forth between storms and their location can either increase or decrease erosion rates.
Define how the wind is created?
- Created by air moving from areas of high pressure to low pressure.
- Strong winds generate powerful waves, has prevailing winds causing higher-energy waves.
Define how waves are created?
- Waves created by wind blowing over surface - circular motion.
- The effect of a wave on the shore depends on its height.
Define constructive waves?
They are created in calm weather and are less powerful than destructive waves.
Define destructive waves?
Are created in storm conditions. They are created from big, strong waves when the wind is powerful and has been blowing for a long time.
Define tides?
Are the regular rise and fall of sea levels, the gravitational pull of the moon and sun cause the tides.
Define currents?
General flow of water in one direction - caused by wind, water temperature or salinity.
Define high energy coast?
- Receive high inputs of energy from large powerful waves.
- Caused by strong winds, long fetches and steeply shelving offshore zones.
Define low energy coast?
- Receive low inputs of energy from small gentle waves.
- Caused by gentle winds, short fetches and gently sloping offshore zones.
Define sediment budget?
The amount of sediment that enters and exits.
More enters then positive sediment budget
More exits then negative sediment budget
Define sediment cells (littoral cells)?
Coastline between two headlands which is a closed system.
Movement of sediment is contained in cell.
11 cells in England & Wales
Define abrasion?
Waves pick up small rocks and throw them at the cliff, breaking off more rocks.
This is when pebbles grind along with a rock platform, much like sandpaper. Over time the rock becomes smoother and worn.
Define hydraulic action?
This is the sheer power of the waves as they smash against the cliff, the air becomes trapped in the cracks in the rock and causes the rock to break apart.
Define cavitation?
As waves recede, the compressed air expands violently, again exerting pressure on the rock and causing pieces to break off.
Define wave quarrying?
When high energy, tall waves hit the cliff face they have the power to enlarge joints and remove chunks of rock in one go through vibration.
Define solution?
minerals are dissolved in the water and carried along in solution. Suspension - fine light material is carried along in the water. Saltation - small pebbles and stones are bounced along the river bed.
Define attrition?
When rocks that the river is carrying knock against each other, they break apart to become smaller and more rounded.
Define the 5 transportation processes? S S S T L
- Solution
- Saltation
- Suspension
- Traction
- Longshore drift
Define SOLUTION as a transportation process?
- Substances that are dissolved get carried along in the water.
Define SALTATION as a transportation process?
- The force of the water causes pebbles & gravel to bounce along the sea bed.
Define SUSPENSION as a transportation process?
very fine material, like silt & clay particles, is whipped up by turbulence and carried along in the water.
Define TRACTION as a transportation process?
Very large particles like boulders are pushed along the sea bed by the force of the water.
Define the 4 sub-aerial weathering processes? SC FT C W&D E
- Salt crystallisation
- Freeze-thaw
- Chemical
- Wetting & drying
- Exfoliation
Define the sub-aerial weathering process SALT crystallisation WEATHERING?
- Caused by saline water.
- Saline water enters cracks in rocks at high tide.
- Tide goes out, rock dries and salt crystals form expanding rock.
Define the sub-aerial weathering process Freeze-thaw weathering?
- Temperature fluctuates
- Water enters cracks
- Cold temperature freezes water expanding in rocks.
- Over time weakens rock to break.
Define the sub-aerial weathering process Chemical weathering?
- Breakdown of rock by changing its chemical composition.
- Carbon dioxide in the atmosphere dissolves in rainwater forming weak carbonic acid which reacts with the rock.
Define the sub-aerial weathering process wetting & drying?
- Some rocks contain clay.
- Clay gets wet, it expands and pressure breaks off rock.
Define weathering?
Breakdown of rock in SITU.
Define 3 types of general weathering categories?
- Mechanical (Physical)
- Biological
- Chemical
Define mass movement?
Shifting of material downhill due to gravity.
Define the 5 types of mass movement? R L R M S
- Rotational slumping (shifts with a rotation)
- Landslides (Shifts in straight line)
- Rockfalls (material breaks up and falls
- Mudflows (Material flows down slope)
- Soil creep
Define unconsolidated rocks?
Are prone to collapse as there’s little friction between particles to hold them together.
Define the 3 coastal landforms caused by EROSION?
- Cliffs & wave-cut platforms
- Headlands & bays
- Caves, Arches & stacks
Define how cliffs & wave-cut platforms are formed?
- Form as sea erodes the land, cliffs retreat.
- Eventually, a notch is formed at high watermark.
- Rock above becomes unstable and collapses creating wave-cut platform.
Define how headlands & bays are formed?
- Bands of alternating hard & soft rock are perpendicular to shoreline.
- Soft rock is eroded quickly forming a bay, harder rocks eroded less quickly and sticks out like headland.
Define how caves, arches & stacks are formed?
- Weak areas eroded to form caves.
- Caves on small headland will form an arch.
- Arch collapses forming stack.
Define the 6 coastal landforms caused by DEPOSITION?
- Beaches
- Spits
- Offshore bars & tombolos
- Barrier islands
- Sand dunes
- Estuary mudflats & saltmarshes
Define how Beaches are formed?
- Constructive waves deposit sediment on shore.
- Shingle beaches are steep and narrow
Define how Spits are formed?
- Longshore drift to deposit material across river mouth leaving bank of sand sticking out in the sea.
- Changes in wind direction can cause spit to curve around a bit.
- Multiple recurved ends of spit called a compound spit.
- Area behind spit is sheltered from waves causes mudflats and saltmarshes to form.
Define how Offshore bars & tombolos are formed?
- Bars formed by spit joining two headlands together.
- lagoon forms behind bar.
- A bar that connects the shore to an island is called a tombolo.