Flashcards in Systems And Processes Deck (104)
Name the two types of geomorphological processes
Define marine processes
Coastal processes that link with the sea
Eg waves, tides, longshore drift.
Define sub-aerial processes
Land based processes that shape the coastline by sub-aerial weathering or mass movement
Name the types of marine erosion
Define hydraulic action
The weakening of rocks by the force and pressure created by waves hitting them
Define wave quarrying
The weakening / breaking off of the cliff face when waves compress air into fissures / joints, which is quickly released when the waves withdraw.
-> like an explosion
The weakening of rocks by sediment in the sea being thrown against the cliffs / wave cut platform.
Material in the sea wear each other down as they collide in the water.
When acidic water dissolves calcium based rocks eg limestone.
-> usually a mixture of sea water and fresh water in localised areas.
How can carbon based rocks be eroded by solution process?
Carbon based rocks eroded by rainwater flow from the land -> pH of this water is usually slightly acidic
How can salt from sea water residue erode rock as part of the solution process?
Sea water residue in rocks evaporates -> salt crystals form -> expand -> weaken / break rock
Name the factors that affect the rate of marine erosion
How does wave steepness affect the rate of marine erosion?
Steeper waves -> higher energy -> more erosive
How does breaking point of waves affect the rate of marine erosion?
Closer the waves break to the shore -> more they erode the rocks (haven't lost energy)
How does fetch affect the rate of marine erosion?
Waves that have travelled a long distance before reaching the shore -> more energy -> more erosive
How does sea depth affect the rate of marine erosion?
Steeper-shelving sea bed by the shore -> higher, steeper waves -> more energy -> more erosive
How does coastal configuration affect the rate of marine erosion?
Headlands attract wave energy through refraction.
Concordant / discordant -> resistant/non rock exposed
How does beach presence affect the rate of marine erosion?
Beaches dissipate wave energy -> lower rate of erosion.
• Steep, narrow beaches -> dissipate flatter waves.
• Flat, wide beaches -> dissipate high, rapid energy output -> because energy is spread out over larger area.
• Shingle beaches -> dissipate steep waves -> due to friction, percolation.
How does human activity affect the rate of marine erosion?
Increase erosion rate -> removing protective sand / shingle.
Decrease erosion rate -> installing sea defences (these may increase erosion elsewhere).
Refers to the characteristics of rocks
Esp resistance to erosion, permeability.
Define differential erosion
The variation in rates that rock types erode
Eg at discordant coastlines.
Define concordant coastline
When rock types run parallel to the shoreline
Eg Lulworth Cove
Define discordant coastline
When rock types run perpendicular to the shoreline
Eg Swanage Bay
Define 'dip' of rocks
Refers to the angle of rock layers in cliffs -> affects steepness of cliffs
Which direction of 'dip' leads to steep cliffs?
Rock strata = horizontal / dipping inland -> steepest cliffs
Which direction of 'dip' leads to sloping cliffs?
Rock strata = dipping seaward
Name the types of marine transportation
Define traction as a process of marine transportation
Large rocks / boulders slide along the seabed in high energy locations due to the movement of the water.
Define saltation as a process of marine transportation
Small stones bounce along the seabed / beach in high energy locations, dislodging other stones