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Eddie's Geography > Landforms weathering and erosion > Flashcards

Landforms weathering and erosion Flashcards

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1
Q

Name the 3 types of rock:

A

Igneous
Sedimentary
Metamorphic

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2
Q

Name the 4 types of weathering:

A

Freeze thaw
Onion skin
Biological
Chemical

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3
Q

How is igneous rock formed?

A

This is volcanic rock.

If it cools under the earth (slowly) it is granite.

if it cools on the surface (fast) it is basalt

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4
Q

How is sedimentary rock formed?

A

When rock particles and plant and animal remains settle at the bottom of the sea.

Over millions of years these compress to form a sold rock.

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5
Q

How is metamorphic rock formed?

A

When sedimentary or igneous rock are exposed to extreme temperature and or pressure due to the earth’s movements.

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6
Q

How does freeze thaw weathering happen?

A 
Water settles in a crack in the rock. 
If it freezes it expands. 
This forces opens the crack. 
After repeated episodes the rock breaks.
The rock fragments are called scree.
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7
Q

How does onion skin weathering happen?

A

Where rocks are exposed to frequent hot then cold (deserts).
In the day they heat and expand.
In the night they cool and contract.
as this process repeats the outside peels off.
The loose rock is called scree.

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8
Q

How does biological weathering happen?

A

Caused by plants and animals.
Burrowing animals break up rocks.
Seedlings fall into cracks and germinate.
Exerting pressure on the crack.

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9
Q

How does chemical weathering happen?

A

Caused by rain containing carbonic acid (dissolved CO2).

Limestone and chalk is calcium carbonate CaCO3. This reacts with the acid.

carbonate + acid = salt + CO2 + H2

Forms calcium bicarbonate which is soluble so the limestone dissolves.

This is why limestone gravestones and pavements weather badly.

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10
Q

What is a river basin?

A

An area of land drained by a river and its tributaries.

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11
Q

What is a watershed?

A

The edge of a river basin area.

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12
Q

What is a source?

A

Where a river starts.

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13
Q

What are tributaries?

A

Small streams or rivers that run into a main river channel.

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14
Q

What is a confluence?

A

The point where a tributary meet up with the main channel.

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15
Q

What is a meander?

A

A bend in the river.

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16
Q

What is an ox-bow lake?

A

Where a meander has got cut off and a lake is formed.

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17
Q

What is a flood plain?

A

The flat land in the lower course of a river which is prone to flooding.

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18
Q

What is an estuary?

A

A wide area near the mouth of the river where the salt water mixes with sea water.

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19
Q

What is a mix of salt water and sea water called?

A

Brackish water.

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20
Q

What is the mouth of a river?

A

The point where the river reaches the sea.

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21
Q

what is a river delta?

A

At the mouth of a river a river can drop its load forming islands.

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22
Q

what is the load of a river?

A

Sediment carried by the river.

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23
Q

What factors influence the size and energy of a wave?

A

The size and energy of a wave is influenced by:

How long the wind has been blowing
the strength of the wind
how far the wave has travelled (the fetch)

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24
Q

What are the 3 processes that occur as a river flows from source to mouth?

A

Erosion
Transportation
Deposition

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25
Q

What are the 4 types of erosion?

A

Attrition
Abrasion
Corrosion
Hydration action

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26
Q

What type of erosion does attrition cause?

A

When particles of load collide and knock pieces off each other.

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27
Q

What type of erosion does attrition cause?

A

Occurs when smaller particles of material rub against the bed and banks of the river.

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28
Q

What type of erosion does corrosion cause?

A

Occurs when acid in the water dissolves particles of rocks from the bed and banks of the river?

29
Q

What type of erosion does hydraulic action cause?

A

The sheer force of the water and air forcing itself into the soil and moving away parts of the bed and banks of the river.

30
Q

What is transportation?

A

Once erosion has taken place the material is the load of the river. it is then carried along by transportation. There are 4 types of transportation.

Traction
Saltation
Suspension
Solution

31
Q

What are the 4 types of transportation?

A

Traction
Saltation
Suspension
Solution

32
Q

What is deposition?

A

When a river down down the load is dumped. This is deposition.

33
Q

Describe traction in river transportation:

A

Traction is the rolling of stones along the river bed.

34
Q

Describe saltation in river transportation:

A

Saltation is the movement of particles leap frogging along the river bed.

35
Q

Describe suspension in river transportation:

A

Suspension is the movement of material that is dissolved in water.

36
Q

Describe solution in river transportation:

A

Solution is the movement of material that is dissolved in the water.

37
Q

What are the features of the upper course of a river?

A

V shaped valleys and waterfalls.
Vertical erosion caused by hydraulic action and abrasion.
The valley sides are then shaped by weather plants and animals.

38
Q

How is a waterfall formed?

A

it is a feature of erosion when a river flowing over hard rock meets a band of softer rock.
1. Hydraulic action forms a step
2. The softer rock is under cut
3 The overhanging hard rock fall off
4 The process continues creating a greater distance between the hard and soft rock.

39
Q

What are the features of the lower course of a river?

A

Meanders, ox-bow lakes, flood plains and deltas.

40
Q

What is a meander?

A

A curve in the rover formed by lateral (side ways) erosion and deposition.
A river is dynamic and constantly changing in shape.

41
Q

What are the features of the outside curve of a meander?

A

River cliff
Fast velocity
Erosion (hydraulic action and vertical Abrasion)
Deeper water

42
Q

What are the features of the inside curve of a meander?

A

River beach / slip off slope
Slow velocity
Deposition
Shallow water

43
Q

How is an ox-bow lake formed?

A

A feature of erosion and deposition:

Outside of 2 meanders are eroded by hydraulic action and abrasion.

The river becomes more curved.

Eventually the narrow neck of land is eroded and water takes a more direct route downstream.

Further deposition cuts off the old meander loop from the river.

44
Q

How is a delta formed?

A

A delta is a feature of deposition:

As large river approach the sea they carry a large amount of load in suspension.

The velocity of the river is reduced as it meets the more powerful sea.

Coarser materials in the load drops first, then finer material.

Over time more and more load is deposited.

The river divides into channels call distributaries flowing around the new islands of land.

45
Q

What is a flood plain?

A

A flood plain is a feature of deposition:

When a river floods water splils out of the original channel.

Larger pieces of load drop forming natural levees (pieces of higher ground) next to the channel.

Finer sediment is dropped further away from the channel.

The flat land onto which this water flows is called the flood plain.

The land will be very fertile as the nutrients carried in the river load are deposited there.

46
Q

Name some well known deltas?

A

Nile delta

Mississippi delta

47
Q

How are beaches formed?

A

Beaches are formed from deposits of sediment.

48
Q

What is longshore drift?

A

Longshore drift is a process of transportation that shifts eroded material along the coastline.

49
Q

Describe the processes that cause longshore drift:

A
  1. Waves approach the coast at an angle.
  2. These call called the swash.
  3. Swash carries sediment up the beach at an angle.
  4. When the wave retreats to the sea this is called backwash.
  5. Backwash carries sediment down the beach with gravity – at right angles (90 degrees) to the beach.
  6. This creates a zig-zag movement of sediment along the beach.
50
Q

What is a spit?

A

Spits are also caused by deposition - they are features that are formed by the process of longshore drift.

51
Q

How is a spit formed?

A

Spits are also caused by deposition - they are features that are formed by the process of longshore drift.

A spit is an extended stretch of beach material that only joins the mainland at one end. They start to form where there is a change in the direction of the coastline.

52
Q

Give an example of a well known UK spit?

A

An example of a spit is Spurn Head, north of the Humber Estuary in the north east of England.

It is fed by the movement of material from the erosion of the Holderness Coast to the north. This is an area of weak boulder clay.

53
Q

What is a salt marsh?

A

Salt marshes may be formed behind a spit. The zone behind a spit becomes a sheltered area.

Water movement slows down and so more material is deposited.

Deposition may form a salt marsh.

54
Q

What are the 4 types of coastal erosion?

A

Hydraulic action
Corrosion
Attrition
Abrasion

55
Q

What is hydraulic action in the sea?

A

The force of the waves against cliffs.

The water traps air in cracks and caves.

The air is compressed forcing the rock to weaken and eventually break.

56
Q

What is corrosion in the sea?

A

Corrosion is caused by the acid in the seawater spray dissolving the rock.

57
Q

What is attrition in the sea?

A

Attrition is caused by pebbles hitting each other in the waves.

It makes the pebbles smaller and rounder and eventually they become sand.

58
Q

What is abrasion in the sea?

A

Abrasion is the effect of waves throwing pebbles against the cliffs.

This erodes the cliff at their base.

59
Q

What are the main features of coastal erosion?

A

Headlands and bays.

Caves, arches, stacks and stumps.

60
Q

How is a bay formed?

A

Where a coastline has alternating areas of hard and soft rock the soft rock erodes faster than the hard rock.

Headlands are created from the areas of hard rock and the bays are eroded from the soft rock between them.

Deposition occurs in the sheltered bays forming beaches.

61
Q

How are caves, arches, stacks and stumps formed?

A

Waves attack a fault in the rock by hydraulic action and abrasion.

The fault is enlarged to form a cave. A blowhole may appear on the headland due to upwards erosion by waves on the roof of the cave.

Hydraulic action and abrasion widen and deepen the cave and eventually cut through the headland to form an arch.

Undercutting weathering and lack of support for the arch lead to collapse leaving a stack.

Weathering and erosion turns the stack into a stump.

62
Q

What is a landslide?

A

A landslide is when rock and or soil on a slope move downwards.

63
Q

What causes a landslide?

A

Landslides are caused by:

Angle of slope
Gravity
Structure of the rock
Saturation of the soil of rock with water
Undercutting the base of the rock by Waves or mining
Building on a slope
Deforestation - tree roots help to hold soil
Tectonic activity

64
Q

What are the three causes of flooding?

A

Climate
Physical
Human

65
Q

What are climatic causes of flooding?

A

Heavy rainfall over a short period of time
Ground already saturated from previous rainfall.
Melting snow and glaciers.
Hurricanes causing wave surges.

66
Q

What are physical causes of flooding?

A

Narrow steep sided valleys cause surface run off the reach rivers rapidly after a storm.
A small river basin area causing rapid surface run off.
Impermeable rock causing rapid surface run off as the water cannot penetrate the rock.
Low lying coastal areas.

67
Q

What are human causes of flooding?

A

Urbanisation can lead to more tarmac that causes rapid surface run off as the water cannot infiltrate the ground.

Deforestation in a river basin, this lads to less water being taken up by tree roots.

Also the loss of tree roots means soil is loose and can be washed into the rover

The diversion of a river or the narrowing of a channel.

68
Q

What are the effects of floods?

A

Buildings are being washed away and damaged.

People and animals can be drowned.

Communications damaged due to closed roads and impassable railways.

Crops can be ruined.

Drinking water can be contaminated by sewage, leading to disease.

Insurance claims can be made if insured items are damaged.

69
Q

What can we do to prevent flooding?

A

Dams can be constructed to control the amount of water being discharged.

Construction of levees and dykes to control water.

Straightening of meanders to enable flood water to escape more quickly.

Afforestation to increase transpiration and infiltration. This removes water.

Sandbagging can prevent flooding in buildings.

Construction of tree defenses.

Eddie's Geography (27 decks)

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