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Geography - Component 1 > Landform processes and change > Flashcards

Landform processes and change Flashcards

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1
Q

Abrasion (fluvial erosion)

A

Stones and materials carried by the river hitting the river bed and banks, wearing them away.

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2
Q

Hydraulic action

A

The sheer force of water hitting the river bed and banks, compressing air in gaps in the soil and rock which causes material to be washed away.

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3
Q

Solution (fluvial erosion)

A

Slightly acidic river dissolves chalk + limestone rocks made from calcium carbonate,

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4
Q

Attrition

A

Rocks carried by the river collide together and broken down, becoming smaller and rounder.

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5
Q

Solution (transportation)

A

Minerals are dissolved in the water and carried along in solution.

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6
Q

Saltation

A

Small pebbles and stones are bounced along the river bed.

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7
Q

Suspension

A

Fine, light material is carried along in the water.

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8
Q

Traction

A

Large boulders and rocks are rolled along the river bed.

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9
Q

How is a V-shaped valley formed?

A
  1. Rivers begin high up in mountains and flow downhill quickly - eroding the landscape vertically.
  2. Using hydraulic action, the river cuts down into the landscape and starts to erode its valley.
  3. The sides of the valley are exposed to freeze-thaw weathering (continuous freezing and thawing of water that has entered cracks in upland rocks, putting pressure on the rocks until small pieces break off).
  4. The freeze-thaw weathering steepens the valley sides as it loosens the rocks, and some of these rocks fall into the river.
  5. The rocks that have fallen into the river cause further erosion and they are transported downstream by the river.
  6. The channel then becomes wider and deeper creating a V-shaped valley between interlocking spurs.
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10
Q

What are the 4 fluvial erosion processes?

A 
Abrasion (river channel)
Hydraulic action (river channel)
Solution (river channel)
Attrition (river bed load)
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11
Q

What are the 4 fluvial transportation?

A

Solution
Saltation
Suspension
Traction

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12
Q

Where and why does deposition occur on a meander bend?

A

Deposition takes place on the inside of a meander as majority of water is on outside of bend. Water on inside has slowest flow + cannot transport load leading to the formation of a slip-off slope.

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13
Q

Where and why does erosion occur on a meander bend?

A

Deeper sections of the river have more water so lateral erosion through abrasion and hydraulic action take place in this section of river. This undercuts the river bank and creates river cliffs.

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14
Q

Describe the formation of waterfalls.

A

The soft rock is eroded quicker than the hard rock and this creates a step.
As erosion continues, the hard rock is undercut forming an overhang.
Abrasion and hydraulic action erode to create a plunge pool.
Over time this gets bigger, increasing the size of the overhang until the hard rock is no longer supported and it collapses.
This process continues and the waterfall retreats upstream.
A steep-sided valley is left where the waterfall once was. This is called a gorge.

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15
Q

Describe the formation of gorges.

A

Waterfall collapses + retreats upstream.

A steep-sided valley is left where the waterfall once was - this is called a gorge.

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16
Q

Describe the formation of floodplains.

A

In lower course, river is carrying a huge amount of sediment (alluvium).
When river floods, excess water spills over the surrounding area.
During flooding, velocity of river is reduced, it loses energy, and deposits sediment, forming the floodplain.
The floodplain is shaped by the lateral erosion of meanders as they migrate downstream + by deposition of material on the inner bends.

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17
Q

Describe the formation of levees.

A

When a flood occurs, the river loses energy.
The largest material is deposited first on the sides of the river banks and smaller material further away.
After many floods, the sediment builds up to increase the height of the river banks and bed.

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18
Q

What are the 3 different types of weathering?

A

Physical
Chemical
Biological

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19
Q

What are the coastal erosion processes that erode cliff faces?

A

Hydraulic action
Abrasion
Solution

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20
Q

What are the coastal erosion processes that erode beach material?

A

Abrasion

Attrition

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21
Q

Keywords for describing the process of longshore drift.

A

Prevailing winds
Swash
Backwash

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22
Q

How are headlands and bays formed?

A

Formed on discordant coastlines where more resistant rock (chalk and limestone) take a long time to erode and therefore create the headlands
Bays have softer rock (sand and gravels) therefore they erode quicker.

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23
Q

How are spits formed?

A

Lsd transports beach material along coast. Where coast changes direction, material is carried there.
Creates news strip of land which projects out into sea + remains attached to land at one end.

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24
Q

How are rock pools formed?

A

Formed when sediment + other material carried by a rivers + coasts scour the floor.
Where exist in the channel floor turbulent flow can cause pebbles to spin around + erode hollows through abrasion.
As holes get bigger even bigger debris can become trapped in the pothole and this material further supports erosion.

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25
Q

How does geology affect the rates of landform change in river and coastal landscapes?

A

Type of rock being eroded

Way in which rock types are laid down.

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26
Q

How does climate affect the rates of landform change in rivers and coastal landscapes?

A

Affects rate of change of river + landforms
Coasts: Prevailing winds determine where depositional features form.
Rivers: Winter months have more rainfall, higher erosion rates as more water flowing in a river.
Extreme weather events: alters landscape by increased fetch + destructive waves (storm).

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27
Q

How does human activity affect the rates of landform change in river and coastal landscapes?

A

Intended: management strategies to reduce impact of erosion of river + coastal landforms.

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28
Q

What four factors cause rivers to flood?

A

Climate
Vegetation
Geology
Urbanisation

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29
Q

How do waterfalls form by glacial erosion?

A

Glaciers carved steep valleys into the landscape, often hanging above one another.
Once glacier melted, water drains from smaller valleys + falls into larger ones.

30
Q

What is freeze-thaw action (physical weathering)?

A

Rainwater enters crack on cliff face.
Night: temp drops, water freezes + expands, makes crack bigger.
During day: ice melts, more water added to larger gap.
Process repeats until rocks fall off.

31
Q

Describe the process of physical weathering (salt crystal growth).

A

Seawater left on rock.
Water evaporates, leaving salt behind.
Salt crystals grow + exert pressure on rock.
Rocks broken apart.

32
Q

Describe the process of biological weathering of plant roots.

A

Plants grow on top of cliff.
Roots push into cracks in the rocks.
Rocks broken apart.

33
Q

Describe the process of biological weathering of burrowing animals.

A

Small animals burrow through soil + into cracks in the rock.

Rock is broken apart.

34
Q

Describe the process of chemical weathering of carbonation.

A

Rainwater enters cracks on the cliff face.
The weak acid reacts with carbonates in limestone.
Cracks get bigger.

35
Q

What is a slip-off slope?

A

A bank of gently sloping deposited material found on the inside bend of a meander.

36
Q

List key features/characteristics of the inside of a meander bend.

A

Shallow water
Slower flow
Slip-off slope
Deposition

37
Q

List key features/characteristics of the outside of a meander bend.

A

Deeper water
Faster flow
River cliff
Erosion

38
Q

Define carbonation

A

Where chemicals in rainwater (e.g. carbonic acid) reacts with chemicals in rock like limestone.

39
Q

Define mass movement

A

When soil, rocks or stones move down a slope.

40
Q

Describe the process of longshore drift.

A

Sediment moved along coastline.
Prevailing wind blows waves into the beach at an angle.
Waves break on shore and as water runs back into sea it carries sediment back down the beach, perpendicular to the angle of the shoreline under the influence of gravity.
Results in zigzag motion as sediment is transported along the coastline.
This can make beaches change shape over time.

41
Q

How is a wave-cut platform formed?

A

The sea attacks the base of the cliff between the high + low water mark.
A wave-cut notch is formed by erosional processes (abrasion + hydraulic action) - this is a dent in the cliff usually at the level of high tide.
As the notch increases in size, the cliff becomes unstable and collapses, leading to the retreat of the cliff face.
The backwash carries away the eroded material, leaving a wave-cut platform.
The process repeats. The cliff continues to retreat.

42
Q

What is a bedding plane?

A

Clearly seen layers of rock in a cliff face.

43
Q

What is a wave-cut platform?

A

A coastal landform made of a rocky shelf in front of a cliff.

44
Q

What is a wave-cut notch?

A

A slot with overhanging rocks that has been cut into the bottom of a cliff by wave action.

45
Q

What is an arch?

A

A natural opening in a cliff where the sea is able to flow through.

46
Q

What is a stack?

A

Vertical pillar of rock left behind after the collapse of an arch.

47
Q

How are caves, arches, stacks and stumps formed?

A

Cracks are formed in the headland through the erosional processes of hydraulic action and abrasion.
As the waves continue to grind away at the crack, it begins to open up to form a cave.
The cave becomes larger and eventually breaks through the headland to form an arch.
The base of the arch continually becomes wider through further erosion, until its roof becomes too heavy and collapses into the sea. This leaves a stack.
The stack is undercut at the base until it collapses to form a stump.

48
Q

Define swash

A

Movement of sediment/sand up the beach by the wave.

49
Q

Define backswash

A

Movement of sand/sediment back down the beach by the wave.

50
Q

What is a spit?

A

A sand or shingle beach joined to the land but projects outwards into the sea in the direction of the prevailing wind.

51
Q

What is an offshore bar?

A

Area of deposition that is slightly off the coastline in the estuary of a river.

52
Q

How are beaches formed?

A

Build-up of sand, shingle and pebbles deposited by waves.

53
Q

How are spits formed?

A

Spits are formed where the prevailing wind blows at an angle to the coastline.
Sediment is carried by longshore drift and moves along the beach via swash and backwash.
When there is a change in the shape of the coastline, deposition occurs.
This creates new strip of land which projects out into sea + remains attached to land at one end (spit).

54
Q

How is an offshore bar formed?

A

Fine silts + sands that are transported by river are deposited at river mouth - form offshore bar.

55
Q

What are rock pools?

A

A pool of seawater between shoreline rocks.

56
Q

What factors affect the rates of landform change in river and coastal landscapes?

A

Geology
Climate
Human activity

57
Q

List the processes and features on the upper course of a river.

A
  • Vertical erosion
  • Weathering
  • Steep gradient
  • Narrow V-shaped valley
  • Potholes
  • Interlocking spurs
  • Waterfalls
  • Rapids
  • Gorges
58
Q

List the processes and features on the middle course of a river.

A
  • Lateral erosion
  • Transportation
  • Asymmetrical channel
  • Floodplain
  • Meanders
59
Q

List the processes and features on the lower course of a river.

A
  • Transportation
  • Deposition
  • Friction is reduced so greater velocity
  • Wide smooth channel
  • Ox-bow lakes
  • Large floodplain
  • Levees
  • Deltas
60
Q

How were V-shaped valley sides formed?

A

Rivers begin high up in mountains, flow quickly downhill eroding landscape vertically.
River cuts deep notch down into landscape using hydraulic action, corrasion + corrosion.
As river erodes downwards, sides of valley are exposed to freeze-thaw weathering which loosens rocks (some of which will fall into the river) + steepens valley sides.
Rocks which have fallen into river help process of corrasion + this leads to further erosion.
River transports rocks downstream + channel becomes wider and deeper creating a V-shaped valley between interlocking spurs.

61
Q

How are the large angular boulders in the stream bed formed?

A

From rivers flowing over steep gradients that have enough energy to erode + transport large quantity of material - load on the river bed is large + angular.

62
Q

How do humans use waterfalls?

A

Tourism

Hydro Electric Power (HEP)

63
Q

What encourages river deposition?

A

River carrying a large load of sediment providing a lot of material for deposition.
Reduction in velocity
Obstruction (something stopping the flow of water)
Bridge support interrupts flow.
Fall in volume of water

64
Q

What 3 landforms are created by longshore drift?

A

Spit, Bar, Tombolo

65
Q

Why is Cornwall more vulnerable to coastal erosion?

A

Destructive waves

Long Fetch

66
Q

How are interlocking spurs formed?

A

In the upper course there is more vertical (downward) erosion.
The river cuts down into the valley.
If there are areas of hard rock (harder to erode), the river will bend around it.

67
Q

How are meanders formed?

A

As river makes its way to middle course, it gains more water + more energy.
There is lateral (sideways) erosion on outside bend due to hydraulic action + abrasion, causes undercutting of the bank to form a river cliff.
Water on inner bend is slower, causing water to slow down + deposit the eroded material, creating a gentle slope of sand and shingle (slip-off slope).

68
Q

How are oxbow lakes formed?

A

Erosion narrows neck of land within meander and as the process continues, meanders move closer together.
When there is a very high discharge (usually during a flood), river cuts across the neck, taking a new, straighter and shorter route.
Deposition will occur to cut off the original meander, leaving a horseshoe-shaped oxbow lake.

69
Q

What are caves, arches, stacks and stumps?

A

Caves, arches, stacks and stumps are erosional features that are commonly found on a headland.

70
Q

How is a beach formed?

A

LSD

When constructive waves lose their energy sand + shingle are deposited normally in sheltered areas such as bays

71
Q

What is a bar?

A

A spit can grow across a bay, joining two headlands together - bar.
They can trap shallow lakes behind the bar - lagoons.
Lagoons don’t last forever + may be filled up with sediment.

72
Q

Describe the formation of a bar.

A

Longshore drift occurs as waves push sediment (which may consist of sand, silt, and clay) towards the coastline at an angle.
Instead of landing on the beach, this sediment begins to build up between the beach and an island, creating the bar + “tying” the island to the mainland.

Geography - Component 1 (13 decks)

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