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Geography - B - Coastal Landscapes > Block 4 (Factors Affecting Coastal Processes + Landforms) > Flashcards

Block 4 (Factors Affecting Coastal Processes + Landforms) Flashcards

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1
Q

What affects wave energy?

A
  • Fetch (longer=more energy)
  • Duration (longer=more energy)
  • Wind Velocity (longer=more energy)
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2
Q

What is fetch?

A

Maximum length of open water over which wind can blow to produce wave

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3
Q

What is the longest UK fetch?

A

SW across Atlantic from Gulf of Mexico

- 4000 km

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4
Q

What is the shortest UK fetch?

A

NE across English Channel from France

- 34km

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5
Q

What is duration?

A

Length of time wind blows over sea to produce wave

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6
Q

What waves are formed by low energy?

A

Constructive, spilling

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7
Q

What waves are formed by high energy?

A

Destructive, plunging

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8
Q

What are the 3 factors that impact where wave energy is focused?

A
  • Wave orientation
  • Wave refraction
  • Wave reflection
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9
Q

What is wave orientation?

A

Direction waves come in to coastline

  • Most often from prevailing wind
  • Can be changed by different weather systems, e.g. storms
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10
Q

Outline the process of wave refraction

A
  • Sea shallower near headlands, deeper in bays
  • Waves approaching headland have increased friction with bed, slow down
  • Waves approaching bay not influenced by friction, continue moving at high velocity
  • So, direction of wave energy - ‘orthogonals’ - appear to bend
  • Orthogonals converge on headlands (most erosion)
  • Orthogonals diverge on bays (most deposition)
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11
Q

What is wave reflection also known as?

A

Clapotis effect

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12
Q

Where can wave reflection occur?

A

When wave hits a vertical surface

  • Rocky coastlines with deep offshore platform
  • Steep beaches
  • Cliff face
  • Sea wall
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13
Q

Outline the process of wave reflection

A
  • Platform causes waves to reflect back out to sea
  • Waves don’t break at shoreline
  • Cliffs protected from erosion + rate of recession decreases
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14
Q

What is a standing wave?

A

The interaction between reflected + incoming waves

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15
Q

What is lithology?

A

The make-up of rocks

  • Rock hardness
  • Chemical composition (minerals + solubility)
  • Permeability
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16
Q

What is rock hardness?

A

How hard/soft the rock is

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17
Q

What rock is usually harder/more resistant?

A

Igneous + metamorphic (heated + compressed in formation)

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18
Q

What rock is usually softer/less resistant?

A

Sedimentary (layers that crumble)

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19
Q

Where was the fastest recorded coastal erosion?

A

Sumatra

- 30m volcanic ash eroded /yr after 1883 Krakatoa eruption

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20
Q

Which areas erode fast/slow due to rock hardness in GB?

A

NW erodes slow - granite (igneous) - resistant headlands

SE erodes fast - glacial boulder clay + sandstone (sedimentary) - bays

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21
Q

What is chemical composition?

A

Minerals rocks are composed of + how chemically reactive/soluble they are

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22
Q

Do chemically inert rocks erode fast or slow? Give example

A

Slow - low chemical weathering

- E.g quartzite

23
Q

Do soluble rocks erode fast or slow? Give an example

A

Fast

  • Dissolve in water
  • E.g chalk + limestone (calcium carbonates)
24
Q

What is permeability?

A

Ability of water to enter and pass through rock

25
Q

What is a concordant coastline + its landforms?

A

Different rock types run parallel to coastline

- Coves, cliffs, wave cut platforms

26
Q

Give an example of a concordant coastline

A

Jurassic Coast - Lulworth Cove

  • Resistant layers of purbeck limestone at front + back
  • Less resistant layers of clay + chalk in middle
27
Q

What is a discordant coastline + its landforms?

A

Different rock types run perpendicular to coastline

- Bays, headlands

28
Q

Give an example of a discordant coastline

A

Holderness Coast

  • Resistant chalk cliffs at Flamborough
  • Less resistant boulder clay at Holderness Bay
29
Q

What is structural geology?

A

The way that rocks are geologically arranged

  • Joints
  • Bedding planes
  • Folds
  • Faults
30
Q

What are joints?

A

Blocks of rock in coastal cliffs

31
Q

How do the number of joints affect rock’s resistance?

A

More joints = More susceptible to weathering + erosion, as more lines of weakness

32
Q

Give an example of where joints can be seen

A

Daepo, South Korea

33
Q

What are bedding planes?

A

Surface that separates two successive layers of stratified rock (strata)

34
Q

How do the number of bedding planes affect a rock’s resistance?

A

More bedding planes = More vulnerable to weathering + erosion, as more lines of weakness

35
Q

How does the configuration of bedding planes affect rock’s resistance?

A
  • Tilting landwards: least resistant - slides + slumps common
  • Vertical: medium resistance - rock falls
  • Horizontal: medium resistance - wave cut notch/platform
  • Tilting seawards - very resistant
36
Q

What are faults?

A

Cracks/lines that have opened up in the rock, along which there is movement

37
Q

What causes faults to form?

A
  • Tectonic shift
  • Earthquakes
  • Mass movement
38
Q

What are the 3 types of fault?

A
  • Dip-slip fault
  • Strike-slip fault
  • Oblique fault
39
Q

What is a dip-slip fault?

A

Vertical movement

  • Normal: hanging wall moves down
  • Reverse: hanging wall moves up
40
Q

What is a strike-slip fault?

A

Horizontal movement

  • Right lateral: when standing on one side, other side appears to move to right
  • Left lateral: when standing on one side, other side appears to move to left
41
Q

What is an oblique fault?

A

Vertical + horizontal movement

42
Q

What is a strike?

A

Point where horizontal + tilted planes meet (on a dip-slip fault)

43
Q

What is a dip?

A

Angle of incline (on a dip-slip fault)

44
Q

How does the number of faults impact rock’s resistance?

A

More faults = more susceptible to weathering + erosion, as act as lines of weakness

45
Q

What is a fold?

A

Rock stretched + compressed by earthy movements, causing undulation of rock layers

46
Q

What are the two types of folds?

A
  • Anticlines

- Synclines

47
Q

What are anticlines? Give an example

A

Rock folds up in the middle

- E.g. Saundersfoot, Gower Peninsula

48
Q

What are synclines? Give an example

A

Rocks fold down in the middle

- E.g. Malta Coast

49
Q

How does number of folds affect rock’s resistance?

A

More folds = Weaker, less resistant rock - can form weak area known as a SHATTER ZONE

50
Q

What is porosity?

A

Whether water can be stored in holes in rock

51
Q

What is perviousness?

A

Ability for water to move through cracks in a rock, but not actually enter the rock itself

52
Q

How does permeability affect rock resistance?

A
  • Permeable: water can enter rock + (if porous) can remain inside, increasing density + resistance (e.g. White Cliffs of Dover)
  • Impermeable: water cannot enter rock, rain weighs rock down (e.g. clay) so it’s more susceptible to mass movements (e.g. slumps)
  • Permeable over impermeable: water enters first rock, but not second, so a ‘zone of lubrication’ can form, more susceptible to mass movements (e.g. slides)
53
Q

What is the term for erosion not all happening at same rate?

A

Differential erosion

Geography - B - Coastal Landscapes (10 decks)

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