Coasts Flashcards
Input
Additional of matter/energy in a system
Output
Movement of matter/energy out of the system
Store/component
Part of a system where energy/mass is stored
Flow/transfer
Form of linkage between one store/component that involves movement of energy
Dynamic equilibrium
Inputs + outputs are balanced in a system
Open system
Matter and energy can enter and leave the system e.g. coastal system
Closed system
Transfer of energy both into + beyond system boundary but not a transfer of matter
Positive feedback
Enhancing/amplification of an effect by its own influence on the process
Negative Feedback
Effects of an action are cancelled out by subsequent knock on effects
Inputs, outputs, flows + stores at the coast
Inputs = sediment from crushed shells, from eroded cliffs, brought by tides/waves/currents/rivers, energy from currents/wind/waves
Outputs = sediment carried to another area/washed out to sea
Flows = erosion, deposition, transportation
Stores = beaches, spits, sand dunes
Sediment Budget
Balance between sediment being added to / removed from coastal system
Sediment Cells
-Parts of the coastline, generally between 2 major headlands, self-contained for the movement of sediment
-Each cell = closed system (closed coastal sub-system)
-Sediment = largely recycled, rather than significant new inputs/outputs
-Assist coastal management plans
Difference between landform + landscape
Landform = single feature, formed by erosion/transportation/deposition
Landscape = collection of landforms linked together + interrelated as part of a system
Concordant vs discordant coastline
Concordant = alternating laters of hard/soft rock running parallel to the coast
Discordant coastline = alternating layers of hard/soft rock running perpendicular to the coast -> differential rates of erosion
Difference between weathering and erosion
Weathering = takes place in situ, erosion = material is transported
Differences between constructive and destructive waves
Constructive:
-strong swash, weak backwash
-long wavelength- up to 100m
-gentle slopes on beaches
- > deposition than erosion
Destructive:
-shorter fetch
-form steep slopes -> steep beach profile
-powerful backwash
-high waves
Spring Tides
-Sun, moon, earth in straight line
-2 a lunar month
-Large tidal range = high tide at highest, low tide at lowest
Neap tides
-Sun, moon + earth form a right angle
-Alternate weeks
-Small tidal range = lower high tides, higher low tides
Wave refraction
-bending of wave fronts
-waves approach on irregular coastline, refract, energy concentrated on headland -> > erosion here
-energy is dissipated in bay -> erosion is weaker
High energy coastlines
-Rocky beach
-Low deposition
-High erosion
-Creates headlands, cliffs, wave-cut platforms
-Often have long fetches
-Large, powerful waves
Low energy coastlines
-High deposition
-Low erosion
-Sandy beach
-Found where rivers meet sea
-Creates salt marshes, mudflats, coastal plains, beaches, spits
-Small, gentle waves
-Short fetch
Cavitation
Bubbles form in water implode under the high pressure -> tiny jets of water -> erodes the rock
Wave Quarrying
Action of waves breaking against unconsolidated material- scoop out loose material
Flocculation
Clay coagulates where fresh water meets the salt water- becomes larger + heavier so its deposited
Deposition
When velocity of water/wind falls below critical level for particular particle size (can no longer be transported)
Wave refraction
When the undersea topography causes the wave fronts to slow, bend and aim to break parallel to shore
Landscape
the visible features of an area- all of the landforms
Concordant coastline
Alternating layers of hard and soft rock which run parallel to the coast- hard rock acts as a protective barrier
forms coves, long, narrow islands parallel to coast
Discordant coastline
alternating layers of hard and soft rock which run perpendicular to the coast- leads to differential rates of erosion
