Coasts Flashcards
What type of system is the coast?
Open system – interacts with other systems (e.g., atmosphere, tectonics, ecosystems).
What are the key components of a coastal system?
Inputs: Precipitation, wind, wave energy, sediment, sea level changes.
Outputs: Ocean currents, rip tides, sediment transfer, evaporation.
Stores: Beach, landforms, sediment.
Flows: Aeolian processes, erosion, longshore drift, transportation.
How does the Water Cycle affect coasts?
Sea level changes due to glacial/interglacial periods impact coastal processes and landform development.
How does the Carbon Cycle affect coasts?
Global warming increases sea levels, causing storm surges & flooding, impacting ecosystems.
What is a threshold?
A point where change exceeds equilibrium, leading to permanent system changes.
Examples of Positive Feedback:
Groynes trap sediment → increases erosion elsewhere.
Sand dune trampling → removes vegetation, leading to more erosion.
Rising sea levels → more flooding → more erosion & land loss.
Examples of Negative Feedback:
Strong storm waves erode sediment → bar forms offshore → waves break earlier → reduces erosion.
What are the main energy sources in coastal systems?
Wind
Waves
Currents
Tides
What is the role of wind?
Primary source of coastal energy – generates waves.
What is the pressure gradient?
Difference in air pressure determines wind strength.
Greater difference = steeper gradient = stronger wind & waves.
How are waves formed?
Wind blows over the sea → frictional drag → ripples → wave formation
What factors affect wave energy?
Strength of wind
Duration of wind
Fetch (distance wind blows over open water)
Constructive waves characteristics?
6-8 per min
Low wave height, large amplitude
Strong swash, weak backwash
Builds up beaches
Destructive wave characteristics?
10-14 per min
Tall waves, short amplitude
Weak swash, strong backwash
Erodes beaches
What is wave refraction?
When waves bend around headlands and bays due to changes in water depth.
At Headlands, Waves converge → concentrated energy → more erosion.
At Bays, Waves diverge → low energy → more deposition.
What causes tides?
Gravitational pull of the moon & sun.
Two high tides & two low tides per day.
What’s the difference between spring and neap tides?
SPRING- sun and moon align, strongest pull, highest tides
NEAP- sun and moon at right angles, weakest pull, lowest tides
What is tidal range?
The difference between high & low tide.
What are longshore currents?
Waves approach coast at an angle → moves sediment parallel to shore.
What are Rip Currents?
Strong seaward-moving currents, pulling water away from shore.
What is upwelling?
Cold, nutrient-rich water rises from deep ocean to surface.
What are storm surges?
Low pressure & strong winds push water inland
Give the characteristics of a high energy coastline.
Large fetch, strong waves
Erosion > Deposition
Erosional landforms (cliffs, stacks, caves)
Give the characteristics of a low energy coastline.
Sheltered from strong waves
Deposition > Erosion
Depositional landforms (beaches, mudflats)
What are the main sources of sediment?
Rivers – major supplier, esp. in high rainfall areas.
Cliff erosion – rapid in soft rock
Longshore drift – moves sediment along coast.
Wind – transports sand for dune formation. Glaciers – deposit sediment as ice melts.
Offshore – waves/tides bring sediment onto beaches.
What are sediment cells?
Sections of coast, self-contained sediment systems.
11 sediment cells in England and Wales (e.g., Holderness Sediment Cell).
What is a sediment budget?
Positive budget: More sediment = coastline builds seaward.
Negative budget: More sediment loss = coastline retreats inland.
what is weathering?
the breakdown or disintegration of rock in its original place leading to the transfer of material
what are the three types of weathering??
mechanical, biological and chemical
describe what freeze thaw weathering is.
water enters a crack, freezes, expands and forces the crack to widen causing a rock to break off
what is salt crystallisation?
when salt evaporates, it leaves crystals that grow and exert stress on the rock causing it to break down.
how does wetting and drying contribute to weathering?
frequent cycles of wetting and drying cause clay to expand and contract leading to cracks and rocks to break down
what is biological weathering?
occurs when plants, animals or decaying vegetation cause rock breakdown
how does carbonation contribute to chemical weathering?
rain absorbs CO2 forming carbonic acid which dissolves calcium carbonate in rocks
what is oxidation in the context of weathering?
the reaction of rock minerals with oxygen like iron causes rocks to weaken and become more susceptible to further weathering
what is solution in chemical weathering
the dissolving of rock materials due to weak acids reacting with minerals
what is mass movement?
mass movement is the downslope movement of material under the influence of gravity often assisted by rainfall
what are the factors affecting mass movement
cohesion, slope height, grain size, temperature, freeze thaw action, saturation
what is soil creep?
the slowest form of mass movement where soil particles rise and fall creating a zig zag motion and terracettes
describe mudflows
saturated soil flows over weak bedrock reducing friction and causing rapid downslope movements
what is rockfall?
a sudden collapse of individual rock fragments often triggered by mechanical weathering leading to scree
how do landslides occur?
blocks of rock move rapidly downhill along a planar surface often caused by rainfall or earthquakes
what is a landslip/ slump?
a curved mass movement of weak clays and sands underlain by impermeable rock often caused by pure water pressure
what is runoff?
the movement of sediment downhill due to water flowing over the surface entering the littoral zone
how does temperature and climate affect weathering?
warming climates favor chemical weathering while colder promote mechanical
what are the key types of erosion in coastal processes?
abrasion, hydraulic action, wave pounding, weathering and solution
what is hydraulic action?
air trapped in cracks by waves is forced out under high pressure breaking up rock
describe corrasion
when sand and pebbles are flung at a cliff by waves eroding it through abrasion
what is abrasion?
the sandpapering effect where sediment dragged across the shore erodes the cliff face
what is attrition
when rocks and pebbles collide with each other breaking down into smaller rounder pieces
what is wave pounding?
the powerful crashing of waves against the cliff that weakens and breaks apart the rock
what is wave quarrying?
waves cause trapped air in cracks to expand explosively eroding the rock
what is solution/ corrosion?
weak acids in seawater dissolve alkaline rocks causing them to erode
what factors affect erosion?
geology, wave type, fetch, configuration, beach presence, human activity and sub aerial processes
what is traction?
larger objects roll along the seabed staying in contact with the floor
what is saltation?
sediment bounces along the seabed occasionally being suspended
what is suspension?
sediment remains suspended in the water never touching the seabed
what is solution in coastal transportation
dissolved sediment moves along with the water
what is longshore drift
sediment is moved along the coastline by waves approaching at an angle and backwash moving perpendicular
what happens to sediment during LSD
sediment becomes smoother, smaller, spherical and sorted
what is surface creep?
wind slides sediment along the surface causing small particles to move
what is saltation in wind transformation?
wind lifts sand and carries it for distances up to 30m
what is deposition
when sediment is too heavy to be carried by water or the wave looses energy causing sediment to accumulate
what are two types of deposition
marine deposition and aeolian deposition
what factors lead to marine deposition
abundant eroded material, reduced wave velocity, sediment accumulating faster than being removed, waves slowing down
what is flocculation?
the process where clay particles clump together in saltwater and sink due to ionic bonding aiding in estuarine deposition
What is the difference between a landscape and landform?
Landscape- The whole section of land including the sea, coastline, beach and surrounding area
Landform- Individual features that make up the landscape.
What factors influence landforms?
Coastal geology and lithology, nature of tides and waves, climate.
What factors determine coastal landscapes?
High/low energy coastlines, dominant processes (erosion/deposition), human management.
How can coastlines be classified?
Concordant/discordant,
cliffed/flat/graded shoreline, emergent/submergent.
How do headland and bays form?
Differential erosion on a discordant coastline where soft rock erodes faster than hard rock.
Why do headlands experience more erosion?
Wave refraction concentrates energy on headlands, making them more vulnerable.
What happens in bays?
Low-energy waves deposit sediment, forming beaches.
What is a wave-cut platform?
A gently sloping rock surface left behind as a cliff retreats.
How do wave-cut notches form?
Waves erode the base of cliffs, forming a notch that eventually leads to cliff collapse.
What is the angle and maximum length of a wave-cut platform?
5-degree angle, up to 500m long.
How does a wave-cut platform create negative feedback?
It reduces wave energy by causing waves to break earlier, slowing erosion.
How does a cave form?
Erosion enlarges joints and cracks in cliffs.
What happens when a cave grows larger?
It forms an arch.
How do stacks and stumps form?
An arch collapses, leaving a stack, which erodes into a stump.
What is a blowhole?
When vertical erosion creates a hole that water sprays through.
What is a Geo?
When erosion burrows through but the roof isn’t able to carry the weight so falls through
What influences beach characteristics?
Wave energy, sediment type, seasonal changes.
Difference between swash-aligned and drift-aligned beaches?
Swash-aligned: Waves approach perpendicularly, limited longshore drift.
Drift-aligned: Waves approach at an angle, sediment moves via longshore drift.
Examples of mini beach formations?
Berms (high tide ridges), cusps (curved dips), runnels (small ridges from tides).
How does a spit form?
Longshore drift moves sediment along the coast where it accumulates due to a change in coastline shape.
What stops a spit from extending indefinitely?
River flow prevents full extension.
Difference between a simple and compound spit?
Simple spit: One recurved end.
Compound spit: Multiple recurved ends due to changing wind directions.
What is a tombolo?
A sand ridge connecting an island to the mainland
What are barrier beaches and islands?
Beaches- offshore bars which rise above sea level
Islands- colonized by vegetation
What conditions are needed for sand dunes to form?
Large sand supply, strong onshore winds, macro tidal range, vegetation.
What are the stages of dune succession?
Embryo Dunes – Initial accumulation, prone to erosion (80% exposed).
Fore Dunes – Pioneer plants stabilize sand.
Yellow Dunes – Marram grass holds dunes together (20% exposed).
Grey Dunes – Soil formation supports vegetation growth (<10% exposed).
Wasting Dunes – Water-loving plants grow in depressions.
Mature Dunes – Coastal woodland develops.
