coastal processes

Question 1

hydraulic action

Answer 1

force of water exerting pressure on rock surface weakening it

Question 2

wave quarrying

Answer 2

wave with trapped air hits cliff and air forced into cracks
when wave recedes explosive effect of air released

Question 3

abrasion

Answer 3

material hurled at cliff

Question 4

attrition

Answer 4

rocks hit each other and become smaller and rounder

Question 5

solution

Answer 5

dissolving of calcium based rocks such as limestone

Question 6

factors affecting erosion

Answer 6

• steep waves=more erosive
• wave breaks close to cliff= more energy released

-further travelled = more energy

-steep shelving = steep waves

-wider flat beach dissipates high energy better
-shingle beach reduces by friction and percolation

-sea defences may decrease here but increase erosion elsewhere

Question 7

what is lithology

Answer 7

characteristic of the rock
resistant = chalk / granite
soft = clay
jointed = limestone

Question 8

what is concordant coastline

Answer 8

when bands of rock lie parallel to coast
hard rock bands protect from erosion

Question 9

what is discordant coastline

Answer 9

bands of rock like perpendicular to coast meaning bays and headlands form as weak bands are eroded faster than hard

Question 10

how does strata impact erosion

Answer 10

horizontal and inland dip = steep cliff
dip seawards = sloped (varying steepness depending on dip degree)

Question 11

traction

Answer 11

large stones rolled along seabed

Question 12

saltation

Answer 12

small stones bounce along seabed
they can dislodge other stones

Question 13

suspension

Answer 13

fine material such as silt is carried by water
murky water

Question 14

solution

Answer 14

dissolved material transported in water

Question 15

what is LSD

Answer 15

• swash moves up sediment up beach at angle according to prevailing wind direction
• backwash moves perpendicular to beach due to gravity
• this continues and sediment is moved along the beach

Question 16

what is marine deposition

Answer 16

• material dropped due to lowered energy
• happens where waves are low energy or abundance of mateial

Question 17

what is aeolian processes

Answer 17

transport sediment by wind
air moves depending on pressure differentials
large tidal range exposes lots of snad
travels close to ground and short distance
forms sand dunes

surface creep and saltation

Question 18

surface creep (aeolian)

Answer 18

wind rolls or slides sand along surface

Question 19

saltation (aeolian)

Answer 19

wind strong enough to lift grains in airflow for up to 20m

Question 20

what is subaerial weathering

Answer 20

processes that breakdown the coastline.
mechanical/chemical/biological

Question 21

mechanical weathering

Answer 21

FREEZE THAW
- water enters cracks and freezes
- water expands by up to 10% so it exerts pressure on rock widening crack
- melts and rock breaks off

Question 22

biological weathering

Answer 22

PLANT ROOTS
- grow roots into rocks causing rock to flake away

ANIMALS NEST
- birds etc burrow into cliff face

Question 23

chemical weathering (6 types)

Answer 23

SOLUTION
-salt from seawater corrodes rock
-acidic rainwater dissolves carbonate rocks

OXIDATION
- oxygen in water reacts with minerals in rock causing it to disintegrate

HYDRATION
- water and minerals in rock addition reaction causing rock to expand weakens cracks allowing further weathering

HYDROLYSIS
- acidic water reacts with minerals in rock producing dissolvable salts which dissolves rock

CARBONATION
-co2 in rain makes weak carbonic acid. this reacts with calcium carbonate in rocks forming calcium bicarbonate which then dissolves in water
-effective in cold places

ACID RAIN
-acid rain reacts with minerals in rock dissolving it
-due to industry gases in atm

Question 24

mass movement

Answer 24

downhill movement of sediment
can be rapid or gradual

Question 25

landslide

Answer 25

downslope movement of blocks of rock down a flat slide plane, maintaining contact with the cliff surface throughout

in consolidated rocks with joints or bedding planes sloping seawards.

Question 26

rockfall

Answer 26

individual rock fragments break away and fall to base of cliff

very rapid
scree at bottom

Question 27

mudflow

Answer 27

saturated soil flows downhill due to gravity triggered by heavy prolonged rainfall

lobe of material at bottom

Question 28

rotational slip

Answer 28

upper layer saturated and water cant percolate to clay
upper layer heavy
cliff slides down curved slide plane in rotational movement
wave removes slumped material and cliff retreats

scarp at top and foot + toe at bottom

fast, common for sands and clays

Question 29

soil creep

Answer 29

very slow movement of individual soil particles downslope
creates terracettes