Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Geog > C -> 2.3 - 2.6 > Flashcards

C -> 2.3 - 2.6 Flashcards

1
Q

cliff erosion discordant cliff

A
  • groundwater flows through the permeable sands but can’t flow through the impermeable clay, water flow along the sand/clay interface weakens the material leading to slumping
  • surface runoff erosion where groundwater emerges on to the cliff face (impermeable clay)
  • wave cut notch formed in weaker coal, siltstone overhangs the notch
  • resistant rock at the cliff base creates a ‘bench’ feature
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

result is

A

scree slopes in most of the bays

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

black lower basalt caps underlying chalk which

A

protects it from weathering - this can be seen at white rocks further along coast

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

white rocks

A
  • ulster limestone chalk
  • protected from storm waves by the skerries
  • basalt rock cap (on top) protects from sub aerial erosion
  • series of cliffs, caves, arches, stacks, stumps - Gulls Point/ Sliddery cove
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

cave/arch/stack/ stumps process

A
  • starts with headland/ land sticking out of sea
  • headland makes the waves refract
  • erosion processes are concentrated on weak points on the sides of the headland
  • hydraulic action/abrasoion then form caves on the side
  • caves meet, forming tunnel
  • tunnel comes arch, which gets bigger til top of arch collapses and stack remains
  • wave erode stack, stack unstable and collapses, leaving a base
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

cliffs and shore platforms

A
  • starts at the base of a cliff
  • cliffs are vertical slopes
  • breaking waves (swash) erode away at cliff material
  • curved-notch forms along the length of the cliff, weaker points might get caves
  • rock above Is unsupported and collapses
  • cliff line retreats (recession)
  • leaving behind a flat/ slightly sloping area of rock - shore platform
  • this platform is subject to weathering and erosion
  • platforms could be left with so lots of rock pools or small ridges where rock is less/ more resistant
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

marine erosion

A
  • often at headland sites
  • wave cut notch and platform formation
  • rate of erosion/debris varies over time
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

sub aerial weathering

A
  • often at the back shore of bays
  • refraction means lower marine energy
  • cliff degradation increases from above
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

marine erosion dominated profile

A

steep face
active undercutting
limited cliff base debris

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

subaerial process dominated profile

A

curved slope profile
lower angle face
accumulated debris

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Dunluce

A
  • near horizontal/slightly dipping landward strata (17o)
  • 100% basalt (agglomerate) near cliff
  • 25% chalk near sea
  • high tide
  • constructive waves (0.7)
  • variable subaerial weathering
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

positive feedback

A

process or mechanism that causes a change to be increased or exaggerated in the future, taking it further away from dynamic equilibrium, eg during the formation of a sport, the deposition shelters area behind it, encourage further deposition

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

negative feedback

A

process or mechanism that balances change by causing it to be reduced or dampened in the future eg a rockfall due to wave erosion, may protect the base of the cliff and reduce the amount if erosion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

example of equilibrium part 1

A
  • complex cliff profile = different rock types = permeability varies
    eg, Causeway: UB (entablature + colonnade)/ laterite/ LB
  • water permeates through upper basalt (pervious) + laterite (porous), but not LB (impermeable)
  • LB undercut by marine erosion, whilst laterite is saturated with rainwater from above = heavier
  • heavy laterite stress> strength, with lubricated being plane = mass movement
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

example of equilibrium part 2

A
  • material falls into the bays/ onto the wave cut platforms and absorbs wave energy
  • materials break down = used fo abrasion on cliff, until disappears
  • waves attack cliff again = wave cut notch/ platform with cliff retreat = equilibrium
  • until tectonics/ isostatic rebound/ eustatic sea level changes whole situation
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

how does tectonics shape dunluce

A

tectonic events 56-62 million years ago formed the igneous bedrock at dunluce and the anticlines and synclines in rock

17
Q

how does geology shape dunluce

A

type of rock type influences the coastal morphology as harder rock is harder to erode, vice versa

18
Q

how does sea level shape dunluce

A

increased sea levels mean increased volume of water contacting the coast

19
Q

how does wave energy shape dunluce

A

higher wave energy means erosion at a higher, which changes the coastal morphology at Dunluce

20
Q

how does marine sub aerial process shape dunluce

A

rain increases the saturation of the superficial geology/rock, which can increase chances of landslides

21
Q

how does marine processes shape dunluce

A

erosional processes form wave cut notches and platforms at usually headlands, but rate of erosion/ debris varies over time

22
Q

biological weathering - tend to exacerbate rate of other weathering

A
  • live on the rocks, scraping away to get food/ boring a hole in the rock - eg a piddock has a shake with serrated curing - edges
  • holes bored into the rock, becoming weak points for weathering to act
  • seaweed acid - eg, kelp - they have h2so4, so if cells break, the acid dissolves the rock away. rock minerals aren’t bonded together so rock crumble
  • Tree root weathering = seeds fall into cracks, germinate and as plant grows, roots expand and thicker - tree roots exert tensional force and force rock apart.
23
Q

frost shattering and freeze thaw

A

water seeps into cracks in rocks, when water freezes, expands in volume by 9%, exerting tensions force which widens rock, thawing allows more water to enter, and freeze, process repeats until cracks are forced open

24
Q

salt crystallisation

A

saltwater penetrates small cracks or pores in rock at high tide, and evaporates at low tide, leaving precipitated salt crystals, repeated tidal cycles lead to growth of salt crystals until they begin to press against sdes of cracks - tensional processes, granular disintegration. Pans and loafs at eaglehawk neck Tasmania

25
Q

chemical reactions

A

oxidation: addition of oxygen to minerals, especially iron compounds which produces iron oxides and increases volume. rock crumbles away, ie. erosion is much easier
carbonation - rainwater mixed with co2 to form weak carbonic acid ph 5.6, acidic rain mixed with calcium carbonate to form soluble calcium bicarbonate, minerals dissolve in solution
hydrolysis - mineral breakdown to form new clay minerals, plus material in solution, because of water/ dissolved CO2

26
Q

tide comes in

A

salt water penetrates cracks and surface of rock

27
Q

tide goes out

A

salt crystals form on and between the gaps of the rock as water evaporates

28
Q

over time

A

salt crystals grow and push gaps in rock apart

29
Q

pan

A

(Backshore) water pools on the top of the rocks furthest away from the ocean dries the fastest, so salt crystallisation is more intense on the rock surface here.

30
Q

loaf

A

(Nearshore ) opposite to pan rocks are closer to water and experience less evaporation on the surface, so only joints are visibly depressed

31
Q

tessellated pavement history

A

300-60 mil years ago, sediment accumulated and compacted to form base rock siltstone stresses in the rock causes cracks and joints, interaction of joints is what gives tessellated appearance of area.
water evaporates on rock, salt erosion occurs

32
Q

factors that affect rock breakdown

A 
sea level
salt erosion
temperature variation
tectonic pressyre
salt content
human movement 
joints/ cracks
33
Q

Complex cliff erosion at giants causeway

A
  • Differential erosion occurs at varying rates, which is caused by different layers of strata
  • Unconsolidated material such as fluvial alluvium is the weakest and easiest to erode, once saturated sediment can slump
  • Giants causeway is made of entablature (more permeable rocks), easier to erode, which causes it to overhang over the colonnade (less permeable), but it is heavily jointed, so it becomes saturated and heavier, which can exacerbate mass movement
  • Igneous rocks such as basalt and laterite are crystalline rocks which means they are made up of interlocking crystal minerals, more resistant rocks. However this depends on the age, permeability and jointing of the rock
34
Q

Permeable rocks are

A

less resistant, so groundwater can enter the cracks in the rocks, which can exploit joints and reduce stability in the cliff

Geog (52 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions