Physical U2 - coats

Question 1

how do waves affect coast lines? (size, frequency, type, energy produced)

Answer 1

1. destructive waves erode coastlines, creating features like cliffs and wave cut platforms
2. constructive waves deposit material, forming beaches, spits and bars
3. larger, more frequent waves carry more energy, increasing erosion rates and shaping steeper coastlines.

Question 2

how does wind direction affect coastlines?(longshore drift)

Answer 2

1. prevailing wind direction drives longshore drift, moving sediment along the coast and shaping features like spits, bars and tombolos
2. variations in wind direction can lead to irregular sediment deposition and shifting landforms

Question 3

how does tides affect coastlines?

Answer 3

1. high tidal ranges expose more of the coastline to erosion and deposition
2. tidal currents influence sediment movement, shaping estuaries, mudflats and salt marshes

Question 4

how does rock type and structure affect coastlines?

Answer 4

1. resistant rock (e.g. granite) form headland and steep cliffs
2. softer rocks (e.g. clay) erode faster, creating bays
3. rock structures (faults, joints, bedding planes) determine the formation of landforms like arches, caves and stacks

Question 5

how does sub-aerial processes (land-based processes and occur above the waterline such as weathering and mass movement) affect coastlines?

Answer 5

1. weathering (e.g. freeze-thraw, chemical) weakens rocks, increasing susceptibility to erosion.
2. mass movement (e.g. landslides, slumping) affects cliff stability and creates features like rotational scars.

Question 6

how do rivers (where they meet the sea) affect coastlines?

Answer 6

1. river transport sediment to the coast, forming features like deltas and estuaries.
2. at low-energy coastlines, sediment builds up, encouraging deposition and the growth of coastal ecosystems.

Question 7

how does fetch (the distance of open sea that wind blows over to generate waves) affect coastlines?

Answer 7

1. a longer fetch generates larger, more powerful waves, increasing erosion rates and shaping steep, rugged coastlines
2. short fetches result in smaller waves and less dramatic landforms

Question 8

how does long term sea level change (eustatic and isostatic) affect coastlines?

Answer 8

1. eustatic (global) sea level rise creates submergent coastlines (rias, fjords)
2. isostatic (local) change creates emergent features like raised beaches and terraces

Question 9

how does coastal ecosystems (sand dunes, salt marshes and mangroves) affect coastlines?

Answer 9

1. sand dunes and mangroves stabilize sediment, reducing erosion
2. salt marshes develop in sheltered areas, trapping sediment and creating flat, vegetated landforms.

Question 10

how does human activity affect coastlines?

Answer 10

1. coastal defences alter natural processes, disrupting sediment transport
2. urban development and industry increase erosion in some areas, while stabilizing others with hard engineering
3. land reclamation can reduce tidal flow and reshape estuaries

Question 11

what is dynamic equilibrium?

Answer 11

Dynamic equilibrium refers to both forward and reverse reactions occurring simultaneously, at the same rate, while the amount of reactants and products remains unchanged (closed system)

Question 12

how does dynamic equilibrium effect the coastal system?

Answer 12

the coastal system is subject to continuous change due to the variation in the inputs of the system. when there is a balance between the inputs and the outputs then the system is in dynamic equilibrium.
this means that the system can remain in a steady state for periods of time but if one element changes because of an outside influence, it upsets the equilibrium and changes the other element in the system.

Question 13

what is positive feedback? give me a coastal example

Answer 13

a positive feedback is a process in which an initial change will bring about an additional change in the same direction. positive feedback contributes to a large change.
e.g.
—> deposition causes a beach to increase in size. —> larger because causes more friction —> more friction leads to slower waves —> slower waves reduce energy and encourages deposition –

(pretend that example goes in a circle)

Question 14

what is negative feedback and give me a coastal example

Answer 14

negative feedback is a process in which an initial change will bring about an additional change in the opposite direction. negative feedbacks stabilise the system, bringing the system, bringing it back towards its original state.
e.g.
sediment eroded from a beach during a storm —> sediment deposited offshore to form an offshore bar —> waves are forced to break earlier, reducing erosion of the beach —> waves move sediment from offshore bar back to the beach —> dynamic equilibrium.

Question 15

what is backshore?

Answer 15

the area between high water mark and landward limit of marine activity (area only reached by waves during storms)

Question 16

what is foreshore?

Answer 16

the area between high water mark and low water mark. most important zone for marine processes during normal conditions

Question 16

what is inshore?

Answer 16

area between low water mark and the point where waves cease to have influence on land beneath them (seabed)

Question 16

what is offshore?

Answer 16

area beyond the point where waves cease to act on seabed. activity here is deposition

Question 17

what makes up a constructive wave?

Answer 17

• low wave height but long wavelength (up to 100m)
• low frequency (around 6-8 per min)
• stronger swash and weak backwash causes deposition. material is slowly but constantly moved up the beach leading to the formation of ridges (berms)

Question 18

what makes up destructive waves?

Answer 18

• high wave height with shorter wavelength
• high frequency - around 10-14 per min
• stronger backwash and a weak swash therefore material is pulled back down the beach (eroded)
• associated with steeper beach profiles

Question 19

how are both types of waves cause dynamic equilibrium?

Answer 19

most beaches are subject to both types of waves but just at different times.
constructive waves build a steeper beach profile which then encourages waves to become more disruptive as they are associated with a steep profile. with time, the disruptive waves move material back towards the sea which reduces the beach angle and then encourages constructive waves.

this is known as negative feedback and should encourage a state of equilibrium.

Question 20

how are the sources of energy wind and waves conducted? what determines the strength of the wave?

Answer 20

wind is the transfer of energy via the atmosphere. a pressure gradient between an area of high pressure and low pressure results in air moving between the two (from high to low pressure areas).

waves are created by the transfer of energy from the wind blowing over the sea (frictional drag of wind over water).

the energy acquired by waves is due to the fetch (strength of wind and distance its travelled)

Question 21

what is wave steepness?

Answer 21

the ratio of the wave height to the wave length

Question 22

what is wave frequency?

Answer 22

the number of waves per min

Question 23

what is wave period?

Answer 23

the time taken for a wave to travel between one wave length.

Question 24

what is the process of waves breaking?

Answer 24

the circular orbit of a wave is affected by shallow water as the wave approaches the coast. friction with the sea bed causes the base of the wave to slow down. this increases the waves height and wave length shortens, until the upper portion of the wave plunges/ spills forward. the breaking wave is translation of energy up the beach (swash). the return of this water back down the beach (backwash) is the result of gravitational pull. a gentle seabed gradient is more likely to produce constructive waves as friction is acting on the base of the wave for longer. a steep gradient is more likely to produce destructive waves.