rapid fire coastal systems/landscapes Flashcards
(33 cards)
distinguish between an open and closed system
closed system=transfer of energy in/out system boundary but not matter
(carbon cycle, sediment cells)
open system=both transferable
(coasts, ecosystems)
difference between negative and positive feedback
N=effects on action nullified by subsequent knock-on effects (counter-acted; gryones=more deposition=less transportation to neighbouring beach)
P=effects amplified/multiplied (loop/cycle; tourism in florida Orlando, D&P increasing+expansion)
4 major subsystems
Atmo(air)sphere
Lith(land)sphere
Bio(living things)sphere
Hydro(water)sphere
4 types of coast
OFFSHORE beyond influence of waves
NEARSHORE waves are breaking “breakerzone”
FORESHORE low and high water zone (under-tidel/surf zone)
BACKSHORE usually above the influence of waves
constructive VS destructive waves
C=strong swash and weaker backwash. Builds material up the landward side of the beach
D=weak swash and stronger backwash, this carties material away from the beach and can lead to gentle beach profiles/shapes
what is meant by breakerzone
zone within waves approaching commerce breaking, typically in water depths of 5-10 metres
4+ sources of energy in coastal system with features
WIND main input of energy forming waves/sandunes
-also factor of EROSION/TRANSPORTION materials can dispersed (by energy from wind by process of ABRASION
FETCH longer=higher wave energy=bigger waves
WAVES undulations of water surface caused by winds blowing across the ocean + energy transferred by friction
3 factors affecting wave height
fetch; wind speed; wind duration.
change in waves in shallow water
deep water=constant wavelength; waves move into breakerzone and touch seabed=wavelength shortens (frictional resistence); waves become unstable and once depth < 1.3 times waveheight, they break as surf
PROCESS EXPENDS MASS ENERGY USED TO MOVE SAND/SHINGLE
wave refraction
As waves approach a coast they are refracted so that their energy is concentrated around the headland but reduced around bays. Indicated by bending of wave crests leading to them becoming parallel to the shore=swash-alingned. Positive correlation between wave energy and water depth.
3 types of current
LONGSHORE CURRENT (clittoral drift) waves hit the coast at an angle. This creates a flow of water running parallel to the shore RIP CURRENTS stongs moving away from the beach. They are formal when water is piled up along the coast by incoming waves. UPWELLING the movement of cold water from the deep ocean towards the surface.
tides/waves/currents
TIDES controlled by moon (periodic); high/low tide=sea level
WAVES controlled by wind
CURRENTS seasonal/permanent
tidal surges (storms)
- caused by meteorological conditions
- sea level can rise by 1cm for every 1millibat drop in pressure
- strong winds drive the water towards the shore=pling-up water against the coast
low energy VS high energy coast
LOW=low wave energy=deposition>erosion e.g=Baltic sea
HIGH=strong winds; erosion>deposition
e.g. Cornish coast
PVLI (most expensive place to build, scale high to low)
Peak
Land
Value
Intersection
sediment cell
length of coastline & associated nearshore area within which the movement of sand/shingle is largely self-contained. Interruptions to this movement within one cell doesn’t affect neighbouring beaches (closed system)
-11 accross the UK
difference between marine and sub-aerial processes
MARINE those that operate on a coastline and are connected to the sea (waves/tides/longshore drift)
SUB-AERIAL these operate on the land but affect the shape of the coast (weathering/mass movement/run-off)
tombolo/bar/spit
Tomobolo=mainland to an island
Bar=goes across two headlands
spit=carries on simple/compound
marine processes examples
abrasion/corrasion attrition biological weathering and erosion corrosion/solution hydraulic rock quarrying water-layer weathering
marine transportation
TRACTION big boulder dragged along river bay
SALTATION when they bounce
SUSPENSION they now float, thin particles
SOLUTION dissolved
sub-aerial processes examples
freeze-thaw salt crystallisation chemical weathering -hydration -hydrolosis -oxidation -acid rain biological weathering hunan activity mass movement/slumping
cliffs and wave-cut platforms
clif, area of cliff recession, wave-cut platform
- the wider the gap, the more momentum needed for the wave to erode the cliff usually requires high tide/energy waves (negative feedback)
- tide undercutting the rock will lead to the overhang collapsing
- types dependent on structure of strata (inland/horizontal/seaward)
geos, caves, blowholes, arches, stacks, stumps
areas on a stretch of coast have small cracks suseptible to erosion, leading to the crack collapsing firming a geo. waves undercutting geo via corrosion/hydraulic action, flooding the cave which leads to an arch. Roof of arch=no support so weathering via biological weathering e.g. Roof of arch will collapse to form a stack, but via corrosion/hydraulic action leads to a stump
headlands/bays
bay=soft rock (cove)
headland=hard rock (on disordinate coastline; prevailing winds concentrate on headlands which erode)
wave refraction occurs targeting headland as 1st point of contact; gets full force of wave energy, the erosion occurs either side of the headland where the soft rock is.
high energy coast=erosion>deposition= formation of a bay (deatructive waves)
E.G. SELWICK’S BAY, EAST YORKSHIRE BAY
