booklet 2- coastal processes

Question 1

what are sub aerial vs marine processes ?

Answer 1

sub aerial- processes that operate on the land but affect the shape of the coastline —> weathering , mass movement and run off

marine- operate upon a coastline that are connected with the sea e.g. waves, tides, longshore drift

Question 2

geology- what is lithology?

Answer 2

the characteristics of rocks (resistance to erosion, permeability etc ) e.g. Granite vs clay

Question 3

geology of limestone

Answer 3

well jointed, sea can penetrate along lines of weakness= they’re more vulnerable to erosion

Question 4

structure of the rock- concordant vs discordant coastal line

Answer 4

concordant= rocks lie parallel to the coast
discordant= rocks lie perpendicular to the coast

Question 5

what is rock dip?

Answer 5

the steppest cliffs form in rocks with horizontal strata/ that dip inland vs gentle sloping cliffs form in areas that dip towards the coast

Question 6

geology what are some key words

Answer 6

strata
joints
bedding planes
folds
faults
dip

Question 7

geology- what is strata, bedding planes and joins

Answer 7

strata= layers of rocks
bedding planes = horizontal, natural breaks in strata
joints= vertical fractures due to contracting sediment etc

Question 8

geology what is folds, faults and dip?

Answer 8

folds= due to presence from tectonic activity
faults = when stress/pressure to a rock exceeds its natural strength
dip= angle at which rock state lie (horizontally, vertically, dip inland or out to sea)

Question 9

geology- what are the most stable cliffs

Answer 9

horizontally bedded and landward dipping strata —> less chance of landslides etc

Question 10

what are the coastal geomorphological processes ?

Answer 10

deposition
transportation
erosion

Question 11

what are the types of erosion?

Answer 11

hydraulic action
abrasion
attrition
solution/corrosion

Question 12

what is hydraulic action?

Answer 12

water forces air into cracks in rock —> pressure from waves on air —> crack expands —> gets larger so loose blocks of rock are eroded = wave quarrying
if waves large = cavitation occurs —> high pressure air bubbles in wages get trapped in small cracks in rock= they generate shock waves = weakens rock

Question 13

what is abrasion, attrition and solution?

Answer 13

abrasion (also called corrosion) - when breaking waves that are carrying sediment scrape against the rock surface

attrition- rocks in sea worn down as they rub together= become smaller and rounder

solution- acids in seawater can wear away the rock surface attrition

Question 14

what are factors that affect rate of coastal erosion?

Answer 14

• wave steepness and breaking point—> steeper= higher energy = greater erosive power. Waves that break at foot of cliff release more energy
• fetch
• sea depth- steep sea bed= higher , steeper waves
• coastal configuration (headlands attract wave energy)
• beach presence as beaches absorb wave energy
  —> flat , wide beach = spread out energy = shingle beaches can deal with wave energy as the energy can be dissipated through percolation and friction
• human activity e.g. may lead to more erosion downstream etc

Question 15

what are the types of transportation?

Answer 15

traction
saltation
suspension
solution

Question 16

what is traction and saltation?

Answer 16

traction- large stones and boulders rolled along the sea bed and beach by moving sea water —> requires high energy
saltation- small stones bounce on sea bed and beach —> requires high energy as they bounce they may dislodge more particles= more bouncing

Question 17

what is suspension and solution?

Answer 17

suspension- small particles (sand, silt etc) carried along in moving sea water
solution - dissolved materials transported within moving water

Question 18

what is a key transportation process?

Answer 18

longshore drift

Question 19

explain longshore drift

Answer 19

• influenced by prevailing winds = waves approach beach at an angle
• as waves break swash carriers material up the beach at the same angle
• as swash dies away , backwash carries material down the beach at right angles
• process repeats transporting material along beach in a zig zag movement
• groynes and human intervention can get in the way
• how spits are formed

Question 20

what is deposition?

Answer 20

• occurs where waves are low energy (e.g. due to friction, wind slows etc)/where there’s lots of erosion elsewhere = lots of sediment/when there’s lots of constructive waves/sand accumulated faster than removed/ when water percolates into beach material as backwash take it back down the beach
• decrease in velocity of water = deposition
• high energy coastline deposits larger rocks etc vs low energy deposits sand/ smaller material

Question 21

what is aeolian deposition?

Answer 21

• caused by wind —> during day wind is generally from the sea, air moves in response to pressure differences by warmer land and cold sea, large tidal range = sand exposed at low tide = provides supply of sediment to be picked up by the wind and is normally carried a short distance. Sand is transported by wind in 2 ways:
  surface creep (wind rolls or slides sand grains along the surface)
  saltation (wind strong enough to lift grains into air flow)
• marine deposition is carried by sea water and deposited

Question 22

what are the sub aerial processes ?

Answer 22

mass movement
runoff
weathering

Question 23

what is sub-aerial weathering?

Answer 23

• breakdown of rock in situ
• they weaken underlying rocks and allow for sudden movements of erosion to happen easier

Question 24

what are the types of sub aerial weathering?

Answer 24

mechanical/physical- freeze thaw
biological
chemical

Question 25

mechanical/physical weathering

Answer 25

- depend on nature of the climate - freeze thaw (occurs at night temps) —> water enters crack in rock —> it expands as it freezes= forces crack to get bigger due to the pressure it exerts, temp rises and water melts again —> process continues eventually breaking rock completely - where weathering, erosion etc removes overlying material= rock beneath experiences pressure release = rock develops weaknesses as it’s allowed to expand = rock susceptible to erosion etc

Question 26

biological weathering?

Answer 26

- nesting birds and animals that burrow = cause rock to break down - plants grow and their roots enter cracks in rock, grow and cause crack to get bigger - shellfish shells drill into rocks (mainly chalk)

Question 27

chemical weathering

Answer 27

carbonation (more common in cooler locations) —> when rain slightly acidic reacts with carbonate rocks (limestone) = they dissolve —> fossil fuels etc = releases gases to atmosphere that can make rainwater acidic oxidation- iron minerals in rocks react with oxygen in air = causes it to rust and breakdown the rock solution= other salt minerals in rock are dissolved

Question 28

what is mass movement?

Answer 28

- downhill movement of material under the influence of gravity - throughflow and run off caused by heavy rain = make cliffs more unstable = more chance of mass movement

Question 29

what are the types of mass movement ?

Answer 29

land slides rock falls mud flows rotational slip/slumping soil creep

Question 30

landslides and rock falls

Answer 30

landslides occur on cliffs made of softer rocks/deposited material which slip due to lubricated surfaces following heavy rainfall rock falls- breaking away of rocks etc at cliff face —> occurs from cliffs undercut by the sea/on slopes affected by mechanical weathering, earthquakes etc

Question 31

mudflows, rotational slip/slumping and soil creep

Answer 31

mudflows - heavy rain= lots of fine material flows down hill —> soil becomes saturated and if excess water can’t percolate deeper into ground = surface layers become fluid and move downhill rotational slip/slumping - where softer material overlies resistant rocks- usually found on weaker rock that become heavy and saturated—> a large area if land moves down slope in one piece and leaves behind a curved, indented surface soil creep- slow but continuous movement of soil particles downslope normally due to soil moisture

Question 32

effect of sub aerial and marine processes on cliff profiles ?

Answer 32

- marine processes can lead to wave cut notch= cliff easier to collapse - sub aerial = weaken cliff, make it more vulnerable and can cause it to retreat or make it irregularly shaped ALSO SO MANY OTHER EXAMPLES THESE ARE JUST SOME