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Geography - Hazards > Plate Tectonics > Flashcards

Plate Tectonics Flashcards

1
Q

Crust

A

Earths outer shell
Made of 14 plates
Oceanic (5km thick)
Continental crust (30 to 70km thick)

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2
Q

Mantle

A 
Essentially a solid but behaves like a liquid 
(semi-molten layer of rock) 
1000C
2885km
Magma here
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3
Q

Outer Core

A

Liquid metal is in motion
Mainly iron
2270km thick
4000C

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4
Q

Inner Core

A 
Solid Metal
Iron/Nickel
1216km 
5000C - 7000C
Heat source that drives convection
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5
Q

Asthenosphere

A

Soft plastic like rock

The upper mantle, just below the lithosphere

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6
Q

Lithosphere

A

The solid top layer of crust in which plates are formed

Consists of crust and upper mantle

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7
Q

Oceanic Crust Thickness

A

6-10km thick

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8
Q

Oceanic Crust Age

A

<200million years old

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9
Q

Oceanic Crust Density

A

Very Dense

3g/cm3

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10
Q

Oceanic Crust Mineral Content and Rock Type

A

Si Mg

Basalt

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11
Q

Which is denser oceanic or continental crust?

A

Oceanic

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12
Q

Continental Crust Thickness

A

30-70km

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13
Q

Continental Crust Age

A

1500 million - 3.8 billion years old

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14
Q

Continental Crust Density

A

Less dense than oceanic crust

2.7g/cm3

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15
Q

Continental Crust Mineral Content and Rock type

A

Si Al

Various Rocks, e.g granite

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16
Q

Convection currents

A

Draw and label a convection current’s diagram with arrows

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17
Q

Explain Earths heat source.

A

Heat is being produced through radioactive decay of naturally radioactive elements, eg uranium.

Subatomic particles are produced and collide with surrounding material inside Earth, motion equals heat

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18
Q

List 5 pieces of evidence supporting continental drift.

A 
Fossil Fit
Geological Fit
Tectonic Fit
Jigsaw Fit
Paleomagnetism
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19
Q

Jigsaw fit example

A

Eastern South America and west Africa

Coastlines are matched at a depth of 1000m below sea level

20
Q

How can gaps and overlaps in jigsaw fit be explained?

A
  • Sea level rise
  • coastal erosion
  • Coastal deposition
  • Land level changes
21
Q

Geological Fit Example

A

Geology of eastern South America and west Africa were mapped and that ancient rock (2,000 million years old) were continuous from 1 continent to another

22
Q

Tectonic Fit example

A

Fragments of an old fold mountain belt between 400 and 450 million years ago are found in a variety of continents

Caledonian Mountain In Greenland, England, Canada etc

23
Q

Fossil Evidence

A

Fossils found on separate continents, (once connected)

They cannot swim or fly

24
Q

How are paleomagnetism and continental drift linked?

A

New material @ mid oceanic ridge
Earths magnetism randomly flips
Striped pattern in magnetism and match it to age
Due to sea floor spreading

25
Q

Slab Pull

A

@ subduction zones, gravity “pulls” the oceanic plate down into the mantle.
This destroys crust material

26
Q

Ridge push

A

Material pushing out from the ridge

28
Q

Sea Floor Spreading

A

Movement of oceanic crust away from constructive plate margins at mid-ocean ridges

29
Q

Benioff Zone

A

Where plates melt in the mantle due to friction and heat

30
Q

Constructive Margin

A

2 plates move apart leaving a gap in the middle or magma to rise from the asthenosphere and fill the gap

31
Q

Constructive Margin Features

A

Shield Volcanoes - Eyjafallajokull
Earthquakes
Rift Valleys -East African Rift Valley
Mid-ocean Ridges - Mid-Atlantic Ridge

32
Q

Destructive Margin

A

Dense oceanic plate descends beneath less dense continental plate

SUBDUCTION

Magma can rise through cracks in the continental plate and form volcanoes upon reaching the surface

33
Q

Destructive Margin Features

A

Earthquakes
Volcanoes
Fold Mountains
Ocean Trenches

34
Q

Conservative Margin

A

2 plates slide past each other along a fault line

35
Q

Conservative Margin Features

A

Shallow Earthquakes

Fault line - San Andreas

36
Q

Collision Boundary

A

2 plates of similar densities move towards each other causing the material between them to buckle upwards and form fold mountains.

37
Q

Collision Boundary Examples

A

The Himalayas, (fold mountains)

38
Q

Oceanic - Oceanic Margin

A

2 oceanic plates move towards each other
Faster/denser is subducted
Melts in Benioff zone
Less dense molten material arises

39
Q

Oceanic - oceanic Margin Features

A 
Ocean trenches - Mariana Trench 
Island arcs - West Indies
Earthquakes 
Composite volcanoes - Montserrat
Tsunamis
40
Q

Oceanic - Continental Margin

A

Oceanic and continental Move towards each other
Denser oceanic subducts
Melts in Benioff Zone
Less dense molten material rises

41
Q

Oceanic - continental Margin Features

A

Ocean trenches - Peru/Chile Trench
Composite volcanoes - Cotopaxi
Fold mountains – Himalayas

42
Q

Continental- continental Margin

A

Continental plates move towards each other
Both plates have a lower density than asthenosphere
Can’t subduct
Collide and rise upwards

43
Q

Continental - continental Margin Features

A

Earthquakes

Fold mountains – Himalayas

44
Q

Hotspots

A

Small area with unusually high concentration of radioactive elements below the surface

45
Q

Hotspot features

A

Shield volcanoes - Mauna Loa, Hawaii

46
Q

Magma plume

A

Rising column of hot rock at plate margin or through a plate

Geography - Hazards (6 decks)

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