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Hazards > Hazards BK 2 - Plate Tectonics > Flashcards

Hazards BK 2 - Plate Tectonics Flashcards

1
Q

How old is the Earth said to be?

A

4.5 billion years old

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2
Q

List the earths internal structure from the middle to the outside

A

Inner core, outer core, lower mantle, asthenosphere, upper mantle, crust

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3
Q

What is the crust and upper mantle collectively called?

A

The lithosphere

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4
Q

What is the radius of the Earth proximately?

A

over 6000 km

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5
Q

what are the two different types of crust called?

A

Oceanic and continental

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6
Q

what separates the crust from the mantle?

A

The Mohorovičić (MOHO) discontinuity

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7
Q

What is beneath the lithosphere and could be described as semi molten

A

The asthenosphere

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8
Q

What are the two elements that the mantle is made up from?

A

Silica and oxygen

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9
Q

What is the thickness of the mantle?

A

2900 km

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10
Q

What state is the outer core?

A

Semi molten/liquid

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11
Q

what is the thickness of the inner core?

A

5100 km

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12
Q

What is the state of it inner core?

A

Solid

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13
Q

What alloys are always found in the earths core

A

Iron and nickel

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14
Q

What is the temperature of the earths inner core?

A

5 to 6000 Celsius

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15
Q

what is the type of heat called That’s left from the earths formation.

A

Primordial heat

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16
Q

what is the type of heat produced by radioactive decay of isotopes?

A

Radiogenic heat

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17
Q

What is Alfred Wegeners theory of plate tectonics that the majority of people believe?

A

the earths crust and upper mantle layer is cracked and divided into a series of plates that float on the semi molten asthenosphere

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18
Q

why is the continental crust nicknamed sial

A

Because it is dominated by silica, rich, minerals, and aluminium

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19
Q

why is the oceanic crust nicknamed sima

A

Because of the silica in magnesium content

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20
Q

what are some factors of the continental crust?

A

older, lighter, thicker, made of granite, lighter in colour, contains silica and aluminium and can be uplifted

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21
Q

what are some characteristics of the oceanic crust?

A

Younger, heavier, thinner, middle of basalt, darker in colour, contain silica and magnesium, and sink

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22
Q

what does wegeners theory of plate tectonics centre around?

A

The idea that the different crustal plates move in different directions due to convection currents in the mantle, cause in continental drift

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23
Q

What was the supercontinent called when all landmasses were joined together

A

pangeae

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24
Q

What are some geological evidence for plate tectonics?

A

South America and west Africa fit together perfectly
rock sequences in northern Scotland closely agree with one is found in eastern Canada
carboniferous glaciation formation deposits are both found in Antarctica and India, so must have formedtogether, then moved apart

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25
Q

What are some biological evidence for plate tectonics?

A

fossil brachiopods found in Indian limestone are comparable with ones found in Australia
Fossil remains of the reptile mesosaurus are found in South America and South Africa

26
Q

What is palaeomagnetism also known as seafloor spreading?

A

The study of ancient magnetic fields

27
Q

what are constructive margins also called?

A

Divergent plate boundaries

28
Q

What is a constructive margin?

A

Where plates are moving apart are away from each other

29
Q

what is an example of a constructive margin

A

Where the North American plate meet the Eurasian plate in the middle of the Atlantic Ocean

30
Q

how do constructive plate margins work?

A

The two plates move apart through seafloor spreading, as they pull a part subsidence happens, and a rift Valley is formed. This creates a weakness where by magma can penetrate, creating a mid ocean ridge in terms of a volcano.

31
Q

What types of hazards occur at a constructive plate margin?

A

Earthquakes volcanoes are the main hazard

32
Q

what is a collisional margin also known as

A

Destructive plate boundaries

33
Q

explain what happens at a collisional margin

A

Where two continental crust plates move together or towards each other

34
Q

How are food mountains formed at a collisional margin

A

Neither continental plate is subducted, which causes uplift to occur. This creates many fold mountains.

35
Q

What is an example of a collisional margin

A

where the Eurasian plate meets the Indian plate where are the Himalayas are found

36
Q

What hazards occur at a collisional margin?

A

Earthquakes

37
Q

why can Earthquakes not happen at a , collisional plate margin

A

There is no subduction that happens here

38
Q

what is a conservative margin also called

A

A transform boundary or fault

39
Q

What happens at a Conservative margin?

A

Where two plates move alongside each other, sometimes in opposite directions, but mostly in the same direction

40
Q

What process occurs at a Conservative margin?

A

both plates will eventually Jerk apart leading to an earthquake

41
Q

What is an example of a Conservative plate margin

A

why, the Pacific plate and North American plate moves alongside each other in the same direction

42
Q

What is the fault called where the North American and Pacific plate meet?

A

The San Andreas fault

43
Q

Do volcanic eruptions happen at a Conservative plate margin

A

No, because there is no subduction

44
Q

what sort of plates are involved at a destructive plate margin?

A

Continental and oceanic or oceanic and oceanic

45
Q

What is an example of a destructive plate margin involving a continental and oceanic plate

A

where are the South American plate is moving towards the oceanic nasca plate where are the Andes are found

46
Q

what happens when a continental and oceanic plates meet at a destructive plate margin?

A

The continental crust is uplifted on the oceanic crust is subducted, which creates a chain of fold mountains

47
Q

do both volcanoes and earthquakes happen at a continental and oceanic destructive plate margin

A

Yes

48
Q

What is increased where 2 oceanic plates meet at a destructive plate margin?

A

Subduction

49
Q

What is created at both a continental and oceanic plate and oceanic and oceanic plate

A

A deep sea trench

50
Q

what is also created when two oceanic plates converge at a destructive plate margin

A

A volcanic island arc

51
Q

What is an example of where two oceanic plates meet

A

Where are the Pacific and the Philippine plates move together create in the Marianas Trench

52
Q

can volcanic and seismic activity take place away from plate margins

A

Yes

53
Q

what percentage of earthquakes occur away from plate margins

A

10%

54
Q

What are hotspots?

A

Hotspots are found within tectonic plates were, the crust is thin, so McMacken rise to the surface, escaping through cracks

55
Q

what do hotspots tend to create

A

Shield volcanoes

56
Q

What is gravitational sliding also known as ridge push?

A

When gravity causes old and denser lithosphere to slide away from the middle ocean ridge

57
Q

what are deep sea trenches

A

where oceanic and continental plates meet, the denser plate is forced under the light one which causes a deep trench in the ocean

58
Q

what are rift valleys

A

a lowland region that forms when tectonic plates move apart, found on land and in the ocean (created by sea floor spreading)

59
Q

what are island arcs

A

where heat from subduction and friction begins to melt a plate, it begins to rise towards the surface as magma, these eventually reach the surface to form complex volcanoes

60
Q

what is slab pull

A

as a plate moves down into the mantle it pulls the rest of the crust on that plate with it

61
Q

what are some arguments supporting plate tectonics

A

long standing theory so has some truth
associated with other theories like continental drift
a lot of landforms have been created by tectonics

62
Q

what are some arguments supporting gravitational sliding

A

convection currents lack power to move in various directions meaning the plate theory can’t be fully true

both slab pull and ridge push explain what happens at opposite ends of plates

Hazards (13 decks)

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