1. How can coastal landscapes be viewed as systems
System
Inputs
Energy
- Thermal/solar energy
- Kinetic energy
- Gravitational energy
Material
- Offshore sediment
- Fluvial sediment
- Estuary & terrestrial sediment
Processes
- Weathering
- Erosion
- Deposition
- Transport (LSD)-> carries material such as sand, small rocks, scree along coast->
landscape uses this to balance system & restore equilibrium
- Currents
- Tides
Above sea level: sub-aerial
- Weathering: mechanical, chemical, biological
- Mass movements: rockfall, landslides, flows
Below sea level: marine
- Erosion: hydraulic action, pounding abrasion, solution
- Transport: traction, saltation, suspension, attrition
- Deposition
Outputs
Energy
- Waves dissipate energy to other systems
- Kinetic energy lost- via constructive waves
Material
- Sand, silt & clay
- Organic matter
Landforms are inter-related by flows of energy
Solar energy-> biological weathering-> veg growth on cliffs & shoreline
Kinetic energy-> wind energy-> formation of waves-> transfer to LSD
Kinetic energy-> wind energy-> aeolian processes moving material from base of cliffs
Gravitational energy-> mass movements, tides
Landforms are inter-related by flows of material
Weathering-> adds to beach store
Mass movement-> adds to scree store
LSD-> adds to beach store
Tides & currents-> move sediment to offshore stores
, Factors influencing geomorphic processes
1) Winds
- Water level rises when winds are strongest generating significant wave action
2) Tides
Small tidal range
- Focuses erosion at the base of the cliffs
- But overall wave energy is less reducing the risk of cliff faces subject to sub aerial
processes-> e.g. the Med
Large tidal range
- During high tide the base of cliffs are submerged, during low tide they're exposed to air->
this alternating submersion & exposure prevents continuous erosion of base of cliffs
- But mean a higher rate of coastal erosion of cliffs, headlands etc = features like wave-cut
platforms, notches etc
3) Geology
Lithology (physical & chemical composition of rocks)
Weak lithology
- Clay = weak bonds-> little resistance to erosion & mass movement
- Chalk & limestone = soluble in weak acids-> vulnerable to carbonation
Resistant lithology
- Basalt = composed of dense interlocking crystals with few joints & faults-> highly resistant
to weathering & erosion
Structure (individual properties of rock, e.g. bedding, joinint, faulting, permeability etc)
Joints- fractures with no significant displacement
Faults- fractures with significant displacement & or movement
Porosity
Porous sedimentary rocks - vulnerable to erosion & weathering processes as water can infiltrate
& dissolve minerals in rock & weaken structure
4) Currents
Driven by earth’s rotation-coriolis effect- causing ocean currents to veer right in N
hemisphere, left in S hemisphere & winds
Warm ocean currents
- Transport heat energy from low latitudes to the poles drive onshore winds
- Carrying energy & sediment-> increases risk of erosion: wave action, abrasion
Cold ocean currents
- Transport cold water from the poles towards the equator, driven by offshore winds
- Carrying less energy & sediment-> less erosion & deposition
Coastal landscapes can be viewed as systems:
Self regulation takes place to restore balance (e.g. = positive or negative feedback)
Equilibrium (takes place seasonally)
- Amount of energy entering a system = energy dissipated (without changing
morphology = steady state equlibrium)
