Coasts Flashcards
(30 cards)
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
