1.1.5 - processes of coastal weathering, mass movement, erosion and associated landforms

Question 1

what are the three processes of mechanical weathering?

Answer 1

freeze-thaw weathering - repeated freezing of water in cracks, the thermal expansion breaks of sections

saltwater crystal growth - the salinity of seawater, crystals develop and exert pressure on the side

wetting and drying - repeated we/dry, minerals expand and break off cracks

Question 2

what are the four processes of chemical weathering?

Answer 2

solution
oxidation
hydration
chelation

Question 3

define chelation?

Answer 3

the organic acids from plant roots bind to metal ions, causes weathering

Question 4

define oxidation?

Answer 4

adding oxygen in water affects rocks with higher iron content

Question 5

define hydration?

Answer 5

minerals absorb water, weakens the structure, more prone to weathering

Question 6

define solution?

Answer 6

acidity of seawater dissolves weaker rocks

Question 7

what is biotic weathering?

Answer 7

plants/vegetation form roots in cliff faces, causes cracks and rocks to fall burrowing animals in sand dunes and softer rock faces

Question 8

what is mass movement?

Answer 8

the downslope movement of material under the influence of gravity and level of lubrication

Question 9

what are the five types of cliff rapid mass movement?

Answer 9

rockfalls, rockslides, rock toppling, rotational slides, slumps

Question 10

what occurs during a rockfall?

Answer 10

blocks of rock fall to the cliff foot from weathering

Question 11

what occurs during a rockslide?

Answer 11

blocks of rock slide down the cliff face from weathering

Question 12

what occurs during rock toppling?

Answer 12

blocks of rock fall seaward from weathering

Question 13

what occurs during rotational slides?

Answer 13

large sections of the cliff fall and stay fully formed at the sea base, leaving a conclave shape in the coastline

Question 14

what occurs during slumps?

Answer 14

permeable rock on top of impermeable, lubricates rock making mudflows

Question 15

what is types of slow mass movement?

Answer 15

creep

Question 16

what occurs during creep?

Answer 16

the extremely slow movement of material downslope

Question 17

what are the four types of marine erosion?

Answer 17

hydraulic action, attrition, abrasion, solution

Question 18

what occurs during hydraulic action?

Answer 18

where waves break on cracks, forcing air inside of them, creating more cracks, therefore weakening the rock to other types of erosion

Question 19

what occurs during attrition?

Answer 19

where rocks bang against each other, getting smaller and rounder

Question 20

what occurs during abrasion?

Answer 20

material in the sea, act like sandpaper wearing down the coast.

Question 21

what occurs during solution?

Answer 21

the acidity of seawater dissolves softer rock, like limestone

Question 22

what are the cliffs and shore patterns determined by?

Answer 22

the geology, the balance of erosion and sub-ariel processes, inherited characteristics

Question 23

how does the geology of the coast determined the cliff profile/shore processes?

Answer 23

harder rock forms steeper cliffs due to its stability (e.g. cave, arch, stack, stump)

softer rock forms low-gradient cliffs and beaches due to its instability

Question 24

how are erosion and subaeriel processes in balance determine a cliff?

Answer 24

energetic waves, erode the cliff but also remove debris from weathering that would otherwise protect the cliff from further erosion

Question 25

how do a cliffs inherited characteristics determine its cliffs?

Answer 25

the sea will reshape a cliff that would formerly be created by subaerial processes

Question 26

what are the sequence of events leading to cliff retreat?

Answer 26

- wavecut notch formed by erosion/corrosion at the base of cliffs, undermines the cliff and causes vertical cliff collapse as the force of gravity becomes too much (list erosional methods) - causes wider wave-cut platforms from the fallen rock -generally occurs at micro-tidal areas.

Question 27

what are the factors in which cliff retreat is due to?

Answer 27

foreshore processes (beach erosion) cliff processes (weathering, seismic) cliff response (mass movement) coastal forcing (tides, waves) slope forcing (rain, temperature)

Question 28

at what rate does limestone erode at per year?

Answer 28

1cm

Question 29

at what rate does chalk erode at per year?

Answer 29

10cm

Question 30

at what rate does clay erode at per year?

Answer 30

10m

Question 31

at what rate does unconsolidated galcier deposits erode at per year?

Answer 31

100m

Question 32

how does a wave-cut platform occur?

Answer 32

flat expanses of gently sloping rock at the foot of a cliff extending out to sea, typically made of fallen cliff material that had been rounded by the tide (attrition)

Question 33

where are headlands and bays often found? example?

Answer 33

at disconcordant coastlines, Dorsets World Heritage Site

Question 34

what occurs during blowholes/geos?

Answer 34

air and water are forced into caves by waves, this can lead to vertical tunnels being formed from the force of hydraulic action against the cave, forcing the air upwards due to pressure changes - this is a blowhole these are commonly found in Iceland if the roof of the blowhole collapses, a conclave shape is left in the coastline and sometimes a narrow valley - these are geos

Question 35

what occurs during crack, cave, arch, stack, stump?

Answer 35

- erosion on either side of a headland meet after adjacent caves collapse in on themselves, forming an arch. - the arch then collapses from further erosion, forming a sea stack , which can be further eroded to form a stump.