Coastal Systems And Landscapes Flashcards
Define what a system is
A set of interrelated components working together forming a process
Define Dynamic Equilibrium
Rate of input + output in a system are equal to
Define what positive feedback loop
When a process or change in conditions causes a change to the landscape causing it to be more likely to happen again
Define what a negative feedback loop is
When a process or change in conditions causes a change in the landscape making change less likely to happen again
How are waves created
Created by the transfer of energy from the wind blowing over the surface of the sea.
Why do waves break
As waves enter shallower waters waves circular orbits begin to become influenced by friction from the seabed, causing it to become elliptical (oval). Over time this friction slows the wave so much that it causes the wave to break.
What waves occur on steeper beaches
Destructive Waves
What waves occur on shallower beaches
Constructive waves
Describe the swash and backwash characteristics of a constructive wave
Strong Swash, Weak Backwash
Describe the swash and backwash characteristics of Destructive waves
Strong Backwash, Weak Swash
Explain how headland wave refraction demonstrates negative feedback
- Along a discordant coastline, the soft rock is eroded faster
- This forms bays (soft rock) and headlands (hard rock)
- Waves then concentrate their energy onto the headland reducing rate of erosion on the soft rock
- This causes them to be eroded at the same rate rather than increased on bays, therefore considered negative feedback
Describe what happens at a spring tide
When the sun, moon and earth align in a straight line, tidal raising forces (gravity) are at their strongest, producing the highest monthly tidal range
Describe what happens at Neap tides
When the moon and sun form 2 perpendicular lines to earth the tidal raising forces are at their lowest so gives the lowest monthly tidal range.
Which tidal range increases concentration of erosional processes
Low tidal range
Which tidal range increases exposure to subareal weathering
Low tidal range
Which tidal range reduces concentration of erosion
High tidal range
Which tidal range decreases exposure to subareal weathering
High tidal range
What effect do tides have on a storm surge
At high tide the storm surge is amplified, at low tides the storm surge is weakened
What beach has the highest tidal range in the world
The Bay of Fundy
How large is the roll that riptides play in the formation of coastlines
Very little as riptides are localised
Where do riptides form
Between sandbars
Name at least 3 forms of mechanical weathering
Any From:
- Freeze Thaw
- Wetting + Drying
- Pressure Release
- Salt Crystallisation
- Exfoliation
Describe + Explain the process of freeze thaw weathering
- Occurs when water enters a crack in a rock due to precipitation
- A following period of cooler conditions freezes this water
- As ice is less dense than water it expands, exerting pressure on the rock causing cracks to widen or break open, causing scree to fall to the base of the cliff.
Describe and explain the process of Wetting + Drying weathering
- Rock in the intertidal zone (and just above due to sea spray) may alternate between wet and dry.
- Shale and porous rocks expand when they are wet and contract when they are dry.
- This process repeats causing fissures to develop and the rock can fragment
Describe and explain the process of pressure release weathering
- Once overlaying sediment and material breaks off, sediment undergoes a pressure release.
- This causes it to develop weaknesses through mechanisms in the rock cause it to develop weaknesses, cracks or joints as it is allowed to expands.
Describe and explain the process of salt crystallisation weathering
- When salt water evaporates it drys up
- Salt crystals are left behind and grow over time, exerting stresses on the rocks over time (just like the ice during freeze thaw weathering)
- Salt can also corrode rock, particularly those containing iron
Describe and explain the process of exfoliation weathering
- Dry rock in the sun is likely to absorb considerable amounts of heat
- these warm rocks are then cooled rapidly when in contact with the sea causing repeated expanding and contracting of the rock, causing it to fracture
- some describe this erosion to occur like an onion skin
Describe and explain the process of biological weathering
Any One From:
-Thin plant roots grow and cause cracks in the cliff face, widening any cracks and causing them to break
- Water running through decaying vegetation can become slightly acidic, increasing chemical weathering
- Animals digging burrows into cliff faces can increase fractures
Name at least 3 forms of Chemical weathering
Any 3 from:
- Oxidation
- Hydrolysis
- Hydration
- Carbonation
- Solution
- Acid Rain
Describe the process of Oxidation weathering
The reaction of rock to oxygen e.g. rust can cause weakness in rock, increasing risk of fractures and breakages
Describe the process of Hydrolysis weathering
Where mildly acidic water reacts or combines with minerals in rock, weakening the rock
Describe the process of Hydration weathering
Water is added to minerals in the rock making it more susceptible to further weathering by causing the rock to expand causing it to disintegrate and cracks to form
Describe the process of carbonation weathering
Carbon dioxide reacts with water creating weak carbonic acid. This reacts with calcium carbonate to create calcium bicarbonate. This can dissolve easily in water.
Describe the process of solution weathering
Slightly acidic water/ water dissolving the rock it runs over
Describe the process of acid rain weathering
Nitrous oxides and sulphur dioxide can lead to acid rain forming which can be effective at dissolving certain types of rock
Why are sediment cells considered closed systems
Geographers consider sediment cells as closed systems as nothing is lost or gained. However some fine sediment can move between sediment cells by finding their way past the headland.
Define what a sediment cell is
A sediment cell is a distinct area of coastline, separated from other areas by well defined boundaries such as headlands and stretches of deep water.
Name an issue with the concept of sediment budgets
Any 1 from:
- The cells are based upon the movement of coarser particles rather than the movement of suspended fine material.
- Fine sediments can find their way into other cells meaning this closed cell concept is not always true
Describe the Mass Movement process of soil creep
Soil creep is a heave process whereby individual particles expand and contract due to the physical environment (particularly moisture) causing it to move downhill slowly. This is very common in clay.
Describe the Mass movement process of Slumping
A flow type of mass movement in which a major section of regolith, soil or weakened bedrock comes down a steep slope as a backward-rotating slump block. Common along coastlines on verges of main roads. Usually in weak rock, clay or soil.
Describe the mass movement process of rockfall
The fastest form of mass movement, the free fall or downslope rolling of rock pieces, loosened by weathering. These boulders shatter at the bottom and form a scree slope.