3.3 - Coastal geomorphology processes Flashcards
Define subaerial
Process at base of atmosphere which breaks down the coastline and weaken the underlying rock so a sudden movement of erosion can happen easily
What is a marine process?
Operate upon a coastline and are connected with the sea (LSD, tides)
Define LSD
Long short drift - prevailing winds at an angle to the coastline and swash transports sediment up the beach then backwash transports it towards sea at a right angle.
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What is an offshore current?
E.g. rip current - move material to sea at a right angle. Sediment is deposited t form a sand bank or reshape depositional landforms
Describe upwelling
Movement of cooler water from deep ocean due to surface winds pushing water away.
What is a longshore current
Approach coast at an angle and generate a current running parallel to the shore. Transports sediment and water
3 causes of a current
Wind, water temperature, salinity
Define current
Large movement of water in one direction
What is a rip current
Formed when a series of plunging waves cause a temporary build up at the top of a beach. Met will resistance from breaking waves. Backwash is forced below surface.
Define bore
Wall of water that travels upstream for a considerable distance
What is solution (transportation)
Dissolved material that is not visibly moving
What is suspension
Small particles oved by light currents
What is saltation
Pebbles bounce of sea bed
What is traction
Rocks are dragged/rolled on sea bed
4 reasons why energy flow declines and description
Energy source changes - weaken currents/prevailing winds
Discontinuity in flow - turbulence between opposite currents (end of spit)
Increased friction - more energy needed to big rocks deposited
Increased load - energy of system isn’t sufficient (sudden river discharge or landslip)
What is the different between corrasion and abrasion
Corrasion - throw at cliff
Abrasion - drag along floor (sand paper)
How does the wave steepness impact the rate of erosion?
Wave steepness - high energy = longer fetch = high and steep
What are aeolian processes
Entrainment, transport and deposition of sediment by wind
3 types of weathering
Biological, chemical, physical/mechanical
What is biological weathering?
Action of vegetation and organisms. E.g. seaweed and plant roots
2 examples and processes of mechanical weathering
Freeze thaw = +- 0oc. Water enters crack, freeze and expand up to 10%, exert pressure and crack widens (pressure relief)
Salt crystallisation - sea water enters crack, freeze and expand, evaporate and salt left behind, repeat
Name the 5 types of chemical weathering
Oxidation
Hydration
Hydrolysis
Carbonation
Acid rain
Define mass movement
Downslope movement of material due to gravity
Define rockfall
Blocks dislodged by weathering fall
Define landslide
Block of rock rapidly move along seaward dipping plane
Define rotational slump
Sections of cliff give way on concave surface and rock/soil s unconsolidated
Define mudflow
Storm/intense rainfall - soil lying over impermeable bedrock
Define creep
Slow downslope movement of individual soil particles
Define solifluction
Slow downslope of waterlogged regrowth. End of ice age (thaw)
What influences mass movement (4)
Angle of slope
Rock type/structure
Vegetation cover
How wet ground is
How does the breaking point of a wave impact the rate of erosion?
Cliff = release most energy Beach = energy dissipated
How does the sea depth impact the rate of erosion?
Sea depth, length and fetch - steep = high wave = more energy
How does the material supply impact the rate of erosion?
Beach absorbs energy
How does the morphology impact the rate of erosion?
High energy wave = wide, flat beach
How does the low energy waves impact the rate of erosion?
Narrow, steep beach
How does the rock resistance impact the rate of erosion?
Joints, horizontal or vertical cliff
What is oxidation?
Oxidation - Hydroxide forms and makes Fe rich rocks go brown
What is hydration?
Hydration - Water makes rock expand then disintegrate by expanding to make faults/joints
What is hydrolysis?
Hydrolysis - mildly acidic water reacts with minerals to form clay
What is carbonation?
Carbonation - CO2 + H2O -> weak carbonic acid
H2CO3 + CaCO3 -> Ca(HCO₃)₂ (calcium bicarbonate which dissolves easily in water)
What is acid rain?
Acid rain - sulphuric gasses
