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Geography > Coastal landforms and SL changes > Flashcards

Coastal landforms and SL changes Flashcards

1
Q

Backshore

A

Between high-water mark and limit of wave activity
Sand dunes are formed here
Change only usually takes place here during storms

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2
Q

Foreshore

A

Between high-water mark and low-water mark
Most important zone for marine processes
Visible at low tide

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3
Q

Offshore

A

Beyond point where waves cease to impact upon the seabed
Deposition of sediment mainly occurs here

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4
Q

Nearshore

A

Between the low-water mark and the point off the coast where waves no longer have any effect on the land beneath them

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5
Q

3 inputs of coastal systems

A

Coastal geology
Climate
Nature of waves

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6
Q

5 processes in coastal systems

A

Erosion
Weathering
Deposition
Wave refraction
Sea level change

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7
Q

2 outputs of coastal systems

A

Sediment
Landforms

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8
Q

3 types of cliffs

A

Horizontal beds
Seaward
Landward

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9
Q

Horizontal bed

A

Near vertical beds
Produce steep cliffs

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10
Q

Seaward cliff

A

Loose material slides down the bedding planes
Makes it unstable and dangerous

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11
Q

Landward cliff

A

Bedding planes sloping towards land
Relatively steep but stable

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12
Q

5 steps of how a wave-cut platform is formed

A
  1. Destructive waves break at the foot of the cliff
  2. Erosion, hydraulic action and corrasion in particular
  3. Cliff becomes undercut forming a wave-cut notch
  4. Cliff above is weathered and put under stress, eventually collapses
  5. After a series of collapses, a wave-cut platform begins to develop between the high and low water marks
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13
Q

3 steps of how a cave is formed

A
  1. Weakness in the rock of a headland
  2. Hydraulic action exploits the rock
  3. Cliff is undercut and a cave is formed
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14
Q

3 steps of how a blow-hole is formed

A
  1. Cave facing oncoming waves is exposed to full force of the waves applied to the back of the cave
  2. Weathering can erode the top of the cliff
  3. Overlying rocks can be sufficiently weakened and collapse forming a blow-hole
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15
Q

2 steps of how an arch is formed

A
  1. A cave is eroded on either side of a headland
  2. Can erode right through the headland to form an arch
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16
Q

2 steps of how a stack is formed

A
  1. Roof of an arch is eroded by sub-ariel processes and chemical weathering
  2. Roof becomes unstable and eventually collapses creating a stack
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17
Q

2 steps of how a stump is formed

A
  1. A stack is subject to erosion, upper part of the stack is weathered, base of the stack is eroded
  2. Over time the whole stack collapses creating a stump
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18
Q

Beach

A

Accumulation of sediment to create a depositional landform

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19
Q

Swash-aligned beach

A

Waves approach perpendicular to the coast
Limited longshore drift

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20
Q

Drift-aligned beaches

A

Waves approach at an angle
Sediment travels along the beach
Longshore drift

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21
Q

2 types of spits

A

Simple
Compound

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22
Q

Simple spit

A

Straight or recurved but do not have minor spits along their landward edge

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23
Q

Compound spit

A

Have a series of minor spits or recurved ridges along their landward side

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24
Q

4 steps of how a spit is formed

A
  1. Occurs when there’s a sudden change in coast direction (estuary/river mouth)
  2. Longshore drift continues to deposit sediment in line with the coast but at sea
  3. Changes in wind/wave refraction leads to a curved spit
  4. Multiple curved ends cause a compound spit
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25
Q

Example of a simple spit

A

Spurn Head, Humberside

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26
Q

Example of a compound spit

A

Hearst Castle, Hampshire

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27
Q

2 steps of how a tombolo is formed

A
  1. Longshore drift causes a spit to grow out and connect to an island from the mainland
  2. Waves moves around the island, when waves meet at the other side of the island, energy falls and material is deposited
28
Q

2 ways a tombolo can be formed

A

Longshore drift
Wave refraction

29
Q

Barrier beach

A

Where a spit extends across a bay and joins two headlands together

30
Q

Tombolo

A

Island connected to the mainland by a mound or ridge of sediment

31
Q

Spit

A

Long, narrow ridge of deposited sediment which are joined to the mainland at one end and stick out to sea at the other end

32
Q

2 steps of how a barrier beach is formed

A
  1. Longshore drift continues to deposit sediment across a bay
  2. Deposited material joins two headlands together
33
Q

Lagoon

A

Store of water behind a barrier beach

34
Q

2 steps of how a barrier island is formed

A
  1. Formation of a barrier beach between two headlands
  2. Barrier beach becomes separated from the mainland to create a barrier island
35
Q

Barrier island

A

Where barrier beaches become separated from the mainland

36
Q

Example of barrier islands

A

West Frisian Islands, Netherlands

37
Q

3 steps of how an offshore bar is formed

A
  1. Sand is deposited as waves don’t have enough energy to carry the sediment to shore
  2. Absorb wave energy so reduce impact of wave energy
  3. Act as sediment sinks
38
Q

8 steps of how a sand dune is formed

A
  1. Wind blows sand landwards from beach
  2. Large tidal range allows the sand to dry, therefore light enough to be transported by the wind to the back of the beach
  3. Dunes develop due to vegetation succession
  4. Pioneer species (couch grass) create embryo dune and help to stabilise the sediment
  5. Dunes grow and become out of reach of high tide and become yellow dunes
  6. More sand accumulates and organic matter (humus) is added, called grey dunes
  7. Dune slacks occur between the dunes the water table is at the surface
  8. Mature dunes are the climatic climate when trees are able to colonise the area to create woodland
39
Q

Embryo dune (6)

A
  • less than 1 metre
  • 80% exposed sand
  • humus content <1%
  • pH 8-8.5
  • couch grass, sea rocket
  • ‘fore dunes’
40
Q

Yellow dune (5)

A
  • 5 metres
  • 20% exposed sand
  • humus content 2.5%
  • pH 7.5
  • marram grass
41
Q

Grey dune (5)

A
  • 8-10 metres
  • <10% exposed sand
  • humus content 10%
  • pH 6.5
  • low shrubs (brambles)
42
Q

Dune slack (4)

A
  • humus content 25%
  • high moisture levels
  • pH 5.5
  • aquatic plants
43
Q

Woodland (4)

A
  • 100% vegetation cover
  • humus content 40+%
  • pH 4.5
  • gorse, oak trees, pines
44
Q

Succession

A

Cumulative change in the types of plant species that occupy an area of land through time

45
Q

2 types of estuarine landforms

A

Mudflats
Saltmarshes

46
Q

steps of how a mudflat/saltmarsh is formed

A
  1. Formed at low energy coastlines
  2. Flowing water carrying lots of suspended sediment meets saline sea water which causes flocculation to happen as clay particles join together (aggregate)
  3. Larger, heavier particles sink to the bed of an estuary or behind a spit
  4. They become exposed at low tides and can become saltmarshes where vegetation grows
47
Q

Sea level

A

Mean level between high tide and low tide

48
Q

Eustatic sea level change

A

Change in the relative level of sand and sea due to rises and falls in the global sea level

49
Q

Isostatic sea level change

A

Rise and fall of land in relation to the sea level

50
Q

3 causes of isostatic change

A

Tectonic activity
Glaciation
Post-glacial readjustment

51
Q

Tectonic activity impacting sea level change (I)

A

Land can move up and down with tectonic activity
Making the sea level rise/fall

52
Q

Glaciation and post-glacial readjustment impacting sea level change (I)

A

During ice ages, glaciers and ice sheets form over land in cold areas
Puts pressure on the mantle and causes the land surface to be pressed
After the ice age when the ice melted, caused the aesthenosphere to rebound back up (isostatic recovery)
Causing relative sea level rise

53
Q

3 causes of eustatic sea level change

A

Thermal expansion of water
Changes in ice sheet extent
Tectonic activity

54
Q

Thermal expansion of water (E)

A

As water heats up, it expands
Mass of the ocean stays the same but warmer oceans have a larger volume to occupy more space
Causing sea level rise

55
Q

Changes in ice sheet extent (E)

A

Ice forms on land during glacial periods, removes water from other stores including oceans
Causing sea level fall
When ice melts on land, sea levels then rise

56
Q

Tectonic activity (E)

A

New land can be formed when tectonic plates move apart
Takes up space in the ocean
Water is displaced and sea levels rise

57
Q

3 emergent coastline landforms

A

Raised beaches
Relict cliffs
Raised marine platforms

58
Q

3 submergent coastline landforms

A

Rias
Fjords
Dalmatian coasts

59
Q

Previous sea level changes

A

Always been rising

60
Q

9 impacts of sea level change

A
  1. Major UK cities at risk of inundation
  2. UK agricultural land may be lost through flooding and coastal erosion
  3. Major road and rail links are at risk
  4. Power stations, gas and oil terminals often built along the coast are at risk of flooding
  5. Groundwater (aquifers) may become contaminated with sea water
  6. River flooding may increase
  7. Loss of coastal habitats#
  8. Submergence of low-lying islands (Maldives)
  9. Migration of people away from coastal areas
61
Q

Offshore bar

A

Submerged (partly exposed) ridges of sand or coarse sediment created by waves and currents offshore from the coast

62
Q

Raised beaches

A

Where sea level drops relative to the land
What was the beach becomes stranded at the high-water mark
Once above high-tide level, vegetation grows

63
Q

Relict cliffs

A

Caves left above the high-tide level

64
Q

Raised marine platform

A

Relatively flat surface which lies above the current sea level

65
Q

Rias

A

Flooded river mouths/valleys
Example: Mouth of the River Exe, Poole Harbour

66
Q

Fjords

A

Flooded glacial valleys
Very steep sides

67
Q

Dalmatian coasts

A

Where river systems flow parallel to the coast
Parallel to the coastline
Long islands which would have previously been hills along valley sides

Geography (8 decks)

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