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Geography - B - Coastal Landscapes > Block 7 (Aeolian, Fluvial + Biotic Processes, The Characterisation + Formation Of Landforms In Coastal Environments) > Flashcards

Block 7 (Aeolian, Fluvial + Biotic Processes, The Characterisation + Formation Of Landforms In Coastal Environments) Flashcards

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1
Q

What are aeolian processes?

A

Wind processes

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2
Q

What are the landforms associated with aeolian processes?

A

Sand dunes

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3
Q

What is a sand dune?

A

Mount/hill/ridge of sand lying beyond the beach’s high tide mark

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4
Q

What conditions are needed for a sand dune to form?

A
  • Good supply of sand
  • Gentle beach gradient
  • Area of inland space for dunes to develop
  • Onshore winds strong enough to blow sand (greater than its threshold velocity)
  • High/macro-tidal range, so sand can dry out + be transported
  • Available vegetation for colonisation
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5
Q

Outline the process of sand dune formation

A
  • Constructive waves deposit sediment on beach
  • Onshore winds transport sediment inland when they are above threshold velocity (suspension, saltation, creep)
  • Deposition occurs when there is a reduction in velocity (e.g. in lee of obstacle)
  • Sand accumulates + pioneer species grow: EMBRYO DUNE
  • If sufficient sand accumulates, dunes merge: FOREDUNES (2m)
  • More plant colonisation (mainly marram grass) + dunes grow: YELLOW DUNES (10m), that are mobile, moving up to 7m inland/yr
  • Between dunes, slacks (lows) form, sometimes with blowouts+lagoons
  • At back, GREY DUNES form, high colonisation + humus levels (organic matter in soil from decay) that cause grey colour (lichen), lower as less sediment reaches them
  • At very back, MATURE DUNES form, nutrient levels high enough for heath/woodland
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6
Q

What is psammosere succession?

A

Vegetation succession on sand (e.g sand dunes)

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7
Q

What are the 5 types of dunes in the succession?

A
  • Embryo dunes
  • Fore dunes
  • Yellow dunes
  • Grey dunes
  • Mature dunes
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8
Q

Why do sand dunes move inland?

A
  • Wind speeds higher on STOSS side (seaward) - more erosion
  • Wind speeds lower on LEE side (landward) - more deposition
  • Causes inland dune migration of up to 7m per year
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9
Q

What are sand dune blowouts?

A

Areas of bare sand located between sand dunes in dune slacks

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10
Q

How do sand dune blowouts form?

A
  • Significant vegetation loss (waves, animals, humans, etc)
  • Wind removes sand - DEFLATION (as no stabiliser)
  • Windward slope (at back) steepens - wind flow increases, increasing deflation rates (POSITIVE F)
  • When water table reached, deflation stops, sand too wet for transportation (LAGOON left)
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11
Q

Why are plants needed for sand dune formation?

A

Their colonisation binds sand, stabilising dunes so they can develop + grow

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12
Q

What is a pioneer species?

A

First species to colonise dunes - closest to sea

  • E.g. Lyme grass + sea couch
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13
Q

What is climax vegetation?

A

Last species to colonise dunes - furthest from sea

  • E.g. trees
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14
Q

What adaptations do plants have to grow in the sand dune system?

A
  • Low growing (to deal with harsh winds)
  • Halophytic - salt tolerance (to deal with high salinity)
  • Xerophtic - drought resistant (to deal with low water levels)
  • Able to cope with low nutrient levels
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15
Q

Give an example of vegetation found on each type of sand dune

A
  • Embryo: Lyme grass + sea couch (PIONEER)
  • Fore: Marram grass
  • Yellow: Marram grass
  • Dune slacks: Rushes (in water)
  • Grey: Lichen + parasol mushrooms
  • Mature: Trees, bushes, heath (CLIMAX)
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16
Q

What is the most important species in sand dune formation?

A

Marram grass

  • Not the pioneer species, but most important in holding sand together to allow dune growth
  • Mainly in fore + yellow dunes
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17
Q

What adaptations does marram grass have?

A
  • Low growing, 60-120cm tall (to combat winds)
  • Halophytic
  • Underground root system + methods to reduce water loss via transpiration, e.g. rolled leaves, sunken stomata, waxy cuticle (to combat low water levels)
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18
Q

What are fluvial processes?

A

Processes associated with rivers + streams

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19
Q

What are estuarine environments?

A

Area in which a river flows into the Sea

  • Affected by fluvial + marine processes
  • Low energy, deposition also areas
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20
Q

What are the main sediment sources in estuarine environments?

A
  • Fluvial/land based
  • Estuary margin
  • Outside estuary (LSD)
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21
Q

What are the major landforms associated with estauries?

A
  • Tidal Mudflats

- Salt marshes

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22
Q

What are the micro-features associated with estuarine environments?

A
  • Channels

- Rills

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23
Q

What are channels?

A

Indents through which running water flows

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24
Q

What are rills?

A

Shallow channels

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25
Q

Where are the channel + rill micro-features found?

A

In estuarine environment - on tidal flats + salt marshes (as water flows over landform, from river out to sea)

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26
Q

What is a tidal mudflat?

A

Extensive, unvegetated depositional area bordering estuary

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27
Q

Where are tidal mudflats found?

A
  • In estuary, at edges where energy is lowest

- Intertidal zone (covered at high tide, uncovered at low tide)

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28
Q

What two processes do tidal mudflats notably experience?

A
  • Sediment sorting

- Bioturbation

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29
Q

Why does sediment sorting happen on tidal mudflats?

A

Differences in energy throughout estuary

  • Highest energy: most seaward (receives wave + tidal energy) + most landward (receives river current energy) points
  • Lowest energy: central zone (particularly edges of central zone)
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30
Q

Where is coaser sediment deposited through sediment sorting on tidal mudflats?

A
  • Most seaward + most landward parts (not enough energy when move into centre to continue carrying large calibre)
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31
Q

Where is finer sediment deposited through sediment sorting on tidal mudflats?

A
  • Central part (small enough to carry into low energy zone where it is deposited)
32
Q

What is bioturbation?

A

Organisms (e.g. lugworms) churning up mudflats by burrowing

33
Q

Give an example of a tidal mudflat

A

Afon Mawddach, West Wales

34
Q

What is a salt marsh?

A

Gently sloping, vegetated areas of intertidal mudflats

35
Q

Where are salt marshes found?

A
  • Intertidal zone

- In low energy areas with deposition: estuaries+behind spits/bars

36
Q

Outline the process of salt marsh formation

A
  • Deposition of mud where river + wave energy is low (mudflat)
  • Pioneer species (halophytic) colonise, encouraging more deposition
  • Height of marsh increases
  • Secondary colonisers invade, succeeding pioneers (closer to land)
  • More deposition + height growth, until less halophytic plants can succeed closer to land
  • Areas furthest from water become more terrestrial than marine, colonised by climax veg, e.g oak trees
37
Q

Moving inland in a salt marsh, how does salinity + tidal exposure change

A
  • Decreasing salinity
  • Decreasing tidal exposure

(So plants inland don’t need to be as adapted as pioneers)

38
Q

What are the two zones in a developed salt marsh?

A
  • Mudflats: covered at normal high tide, uncovered at normal low
  • Sward zone: only covered at spring high tide
    (At very back of these zones are the climax species)
39
Q

What is a halosere succession?

A

Succession characterised by high salinity

- E.g salt marsh

40
Q

Give examples of 2 pioneer species in a salt marsh

A
  • Salicornia
  • Spartina
    (Can tolerate harsh conditions: frequent tide cover, high salinity)
41
Q

Give examples of 2 sward zone species in a salt marsh

A
  • Sea lavender
  • Sea thrift
    (Can tolerate medium conditions: covered by spring tide, medium salinity)
42
Q

Give examples of 2 climax species in a salt marsh

A
  • Ash tree
  • Oak tree
    (Terrestrial: not covered by tides, low salinity)
43
Q

Give an example of a salt marsh

A

Salt marshes on Essex Coast - ‘The Saltmarsh Coast’

Between Blackwater + Crouch estuaries

44
Q

What are biotic processes?

A

Processes completed by living beings

  • Coral reefs
  • Mangroves
45
Q

What is a coral reef?

A

Underwater ecosystem made up of coral polyp colonies held together by calcium carbonate

46
Q

Outline how coral reefs form

A
  • Made up of polyps (small, soft-bodied organisms from jellyfish family)
  • Polyps secrete protective skeleton made from calcium carbonate, that connects them to each other + the seabed
47
Q

How do cold water polyps get their food?

A

Catch food in tentacles as it moves past them in current

48
Q

How do warm water polyps get their food?

A

Get energy from SYMBIOTIC relationship with ZOOXANTHELLAE

  • Mutually benefit
  • Zooxanthellae get nutrients + shelter
  • Polyps get food (zooxathellae are algae that photosynthesise + share their food with polyps)
49
Q

What gives coral reefs their colour?

A

Zooxathellae living on polyps photosynthesising

50
Q

Where do cold coral reefs form?

A
  • Deep cold water
  • Recently discovered (advance in deep sea tech)
  • Corals work independently - no zooxanthellae
51
Q

Give an example of a cold coral reef

A

Darwin Mounds, Scotland

  • 1000 m under North Atlantic
  • First discovered in 1998
52
Q

Where do warm coral reefs form?

A
  • Approx 30degrees either side of Equator
    In specific conditions:
  • Temp: 23-29C
  • Water depth: less than 100m (need light + water coverage)
  • Salinity: 30,000-40,000 ppt
  • Light/clear (for zooxathellae photosynthesis)
  • Clean
  • Well-aerated from good wave action(need good oxygen supply)
53
Q

Where are most coral reefs found?

A

In warm water

- 91% in Indo-Pacific region

54
Q

What happens if reef conditions change?

A
  • Polyps are very sensitive
  • Changes cause them to stress (e.g sea level rise + pollution)
  • Stressed polyps expell zooxathellae - CORAL BLEACHING
  • Polyps lose their food provided by the symbiotic relationship
  • Can die if left unhelped
55
Q

What proportion of the world’s coral reefs have died in the last 30yrs?

A

Over 50%

56
Q

How many reefs will suffer at least one bleach over the next 50yrs?

A

Every reef

57
Q

Why are coral reefs important?

A
  • Natural coastal defence (waves break offshore)
  • Natural carbon sink (store CO2 in calcium carbonate skeletons)
  • Great biodiversity (cover 1% ocean floor, home to 25% ocean species)
  • Potential medical benefits (half research for new cancer drugs is using marine organisms)
  • Food source (can yield 15 tonnes seafood/km sq per year)
  • Employment (tourism, conservation, fisheries)(supports livelihood of over 100 mill people)
  • Economic contributor (boosts tourism - revenue $30 bill per yr)
58
Q

What are the three types of coral reef?

A
  • Fringing
  • Barrier
  • Atoll
59
Q

What is a fringing coral reef? Give an example

A

Reef directly attached to the shore or separated by only a small channel or lagoon
- E.g. South Molokai, Hawaii

60
Q

What is a barrier reef? Give an example

A

Reef separated from shore by a deep channel/lagoon

- E.g. Great Barrier Reef

61
Q

What is an atoll reef? Give an example

A

Roughly circular reef with lagoon in middle, that has risen from submerged volcanic foundations
- E.g. in the Maldives

62
Q

What are the human threats to coral reefs?

A

Fishing
- Overfishing can cause algal growth, reducing sunlight
Agriculture
- Land clearing increases surface run-off which reduces sea clarity
- Chemical pesticides/fertilisers can damage corals
Tourism
- Removal of veg for development, increases surface run off, decreases sea clarity
- More sewage, nitrogen + phosphate near sewage pipes, algal growth
- Demand for more energy, release hot water, raises sea temps
- Destruction for souvenirs
- Diving + snorkelling activities disrupt environment
- Increased waste + pollution

63
Q

What are the natural threats to coal reefs?

A

Hurricanes
- Often produce powerful waves, can destroy coral
- Heavy rainfall increases surface run off, decreasing sea clarity
Global warming
- Fewer areas remain 23-29C all yr
- More threatening events, e.g hurricanes + heatwaves
- CO2 level increase makes sea more acidic, calcium carbonate production harder
Coral diseases
- Approx 30 diseases known about
- Little known about cause + effect, so hard to prevent
- 80% coral lost in last 20 yrs was to disease

64
Q

What are mangroves?

A

Group of tree species that can tolerate high salinity

65
Q

Approximately how many mangrove tree species are there?

A

100

66
Q

What are mangrove forests?

A

Intertidal zones that have been colonised by mangrove trees

67
Q

How are mangrove forests different to salt marshes?

A

Mangrove forests have greater biomass

68
Q

Where are mangroves found?

A
  • Across 118 countries
  • Intertidal zone
  • Often in nutrient-rich estuaries or deltas
  • Most in S+SE Asia (over 40%)
69
Q

What are the conditions in mangrove forests?

A
  • Fertile soil
  • Waterlogged/anaerobic
  • High salinity
  • Affected by tides
70
Q

What are some adaptations of mangroves to deal with conditions in mangrove forests?

A
  • Pneumatophores (straw-like roots that stick out above waterlogged mud to take in oxygen via pores called lenticles)
  • Arenchyma (porous roots below ground with air spaces to improve oxygen flow)
  • Salt glands on leaves (allow secretion of excess salt)
  • Waxy cuticles on leaves (reduce water loss)
  • Seeds remain attached until fertilised (improves reproduction)
71
Q

Why are mangroves important?

A
  • Large biodiversity (including some unique/endangered species)
  • Carbon sink (soils intake double as much C/yr as salt marshes)
  • Natural coastal defence
  • Fishing (fish habitat - provides food + work)
  • Resources (medicines, timber, fertile farming soil, etc)
  • Symbiotic relationship with coral reefs (coral reefs absorb wave energy, mangroves trap sediment to keep water clear)
72
Q

What is a symbiotic relationship?

A

Cooperative, mutual relationship between two species

73
Q

If left naturally, are mangroves threatened?

A

Not particularly - on average growing, reclaiming 3mm from sea/yr

74
Q

How are humans threatening mangroves?

A
  • Overharvesting resources
  • Clearing for agriculture/settlements
  • Shrimp aquaculture
  • Overfishing
  • Damming rivers upstream
  • Pollution (e.g oil spills suffocate trees)
  • Reef destruction/bleaching (destroys symbiosis)
  • Eustatic sea level rise from climate change (cancelling out land regain)
75
Q

Give two examples of coral reefs

A
  • Caribbean coral reefs

- Great Barrier Reef

76
Q

Give an example of a mangrove

A

The Sundarbans

77
Q

Give an example of a mangrove plant

A

Avicennia Marina (‘grey mangrove’)

Geography - B - Coastal Landscapes (10 decks)

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