The Restless Earth

Question 1

Name the layers of the earth?

Answer 1

Inner core
Outer core
Mantle
Crust

Question 2

What are the two types of crust and their characteristics?

Answer 2

Oceanic crust which is denser and thinner

Continental crust which is less dense but thicker

Question 3

How do tectonic plates move?

Answer 3

The heat from the earths core creates convection currents in the mantle. The convection currents work in a circular motion the hot molten rock riding moves the plates on the surface which forms the crust

Question 4

Why is the crust unstable?

Answer 4

Because plates may ,over apart, closer together or slide past each other or even collide into each other. Some of these movements can cause the formation of fold mountains and volcanoes

Question 5

Name 3 tectonic plates?

Answer 5

Eurasian plate 
African plate
South American plate 
North American plate 
Caribbean plate
Indo Australian plate 
Philippine plate 
Pacific plate 
Mascara plate

Question 6

Name the four types of plate margins?

Answer 6

Destructive
Constructive
Conservative
Collision

Question 7

What happens at a destructive plate margin?

Answer 7

Two plates move together, the continental crust stays on top however the denser oceanic crust sub ducts beneath into the mantle were it will melt.

Question 8

What happens at a constructive plate margin?

Answer 8

Two plates move apart from each other and magma rises to fill the gap

Question 9

What happens at a conservative plate margin?

Answer 9

Two plates slide past each other sometimes at the same direction usually not and they can sometimes stick together

Question 10

What happens a a collision plate boundaries?

Answer 10

Two plates both made from continental crust collide into each other neither can be sunk or destroyed

Question 11

What can be caused by destructive plate margins?

Answer 11

Rising magma can cause composite volcanoes
Energy in subduction zones is released as earthquakes
Fold mountains are formed by impact of colliding plates
Ocean trenches are formed

Question 12

What is caused by a constructive plate margin?

Answer 12

Ridges and shield volcanoes are formed by the build up of magma
Volcanoes can form islands if they rise above sea level

Question 13

What is caused by conservative plate margins?

Answer 13

Earthquakes occur when built up pressure forces plates unstuck

Question 14

What is caused by collision plate boundaries?

Answer 14

Fold mountains

Question 15

Give two ways in which earthquakes are triggered by plate movements? (2 marks)

Answer 15

Destructive plater margins

Conservative

Question 16

Give me an example of two destructive plates?

Answer 16

Nazca plate and South American plate

Question 17

Give me an example of a constructive plate margin?

Answer 17

North American plate and the Eurasian plate

Question 18

Give me an example of a conservative plate margin?

Answer 18

Pacific plate and the North American plate

Question 19

What are Ocean trenches and fold mountains and where do they occur?

Answer 19

They are landforms that occur at destructive plate margins

Question 20

How is a fold mountain formed?

Answer 20

Thick sediment layers form in huge depressions called geosynclines under the sea.
Over millions of years the sediments are compressed into rock because of the plates movements.
The sedimentary rocks are forced into folds as the plates move closer.

Question 21

How is an ocean trench formed and where are they formed?

Answer 21

Formed in subduction zones on a destructive plate margin. One wall of the trench is formed by the subduction oceanic crust the other wall is the edge of the continental crust

Question 22

Why are Ocean trenches of little use to humans?

Answer 22

Because they are too deep for us humans to reach the ocean floor to do things such as drill for oil except for short periods of time with expensive machinery

Question 23

What are the two types of main volcano?

Answer 23

Shield volcano

Composite volcano

Question 24

What are the characteristics of a shield volcano and give me an example?

Answer 24

Runny lava that pours out smoothly 
Regular and frequent eruptions 
Not explosive 
Gentle slopes 
Wide base

An example would be Surtsey island near Iceland

Question 25

What are the characteristics of a composite volcano and give me an example?

Answer 25

Viscous lava 
Violent eruptions 
Irregular eruptions 
Cone like shape 
Made of ash and lava 
Steep sides 
Narrow base
Etna in Italy

Question 26

How is a composite volcano and a shield volcano formed?

Answer 26

Shield is were magma rises to fill the gap between two plates on constructive plate margins

Shield is where magma in the subduction zone is under pressure and is forced up to the surface through the cracks on destructive plate margins

Question 27

Why do people live near volcanoes despite the danger?

Answer 27

Fertile soil
People don’t expect them to erupt
Nice scenery

Question 28

What are the features of an earthquake?

Answer 28

The focus is the point at which the earthquake happens
The epicentre is just above the focus where the effects are the worst
Shockwaves radiate out in all directions from the focus

Question 29

How can I measure an earthquake?

Answer 29

The Richter scale to measure the magnitude and the mercalli scale which indicates the impact on the people

Question 30

Explain why many strong earthquakes occur at destructive plate margins?

Answer 30

Tectonic plates that move against each other often get stuck due to friction. Within the subduction Zone of destructive plate margins one plate is being forced underneath another causing energy to build up when they get stuck. So they earthquake produced when they move again are often very strong

Question 31

What are tsunamis and where do they occur

Answer 31

Tsunamis are secondary effects of earthquakes and occur at sea

Question 32

How does a tsunami happen?

Answer 32

Two plates get stuck and build up tension
An underwater earthquake happens as the tension breaks snapping one plate edge upwards
The sea bulges upwards creating a huge swell of water
The swell reaches the coast and travels very quickly inland