Plate Margins

Question 1

The Earth is made up of different layers, what are they?

Answer 1

The inner core is in the centre and is the hottest part of the Earth. It is solid and made up of iron and nickel with temperatures of up to 5,500°C.
The outer core is the layer surrounding the inner core. It is a liquid layer, also made up of iron and nickel.
The mantle is the thickest section of the Earth at approximately 2,900 km. The mantle is made up of semi-molten rock called magma.

Question 2

What is the theory of plate tectonics?

Answer 2

Where convection currents converge, plates move towards each other. The movement of the plates, and the activity inside the Earth, is called the theory of plate tectonics.

Question 3

What happens in the theory of plate tectonics?

Answer 3

The crust is the outer layer of the Earth. It is a thin layer between 0 - 60 km thick. The crust is the solid rock layer upon which we live. It is either continental or oceanic. The earth’s crust is broken into plates. Heat rising and falling inside the mantle creates convection currents generated by radioactive decay in the core. The convection currents move the plates. Where convection currents diverge near the Earth’s crust, plates move apart.

Question 4

Whats meant by a conservative plate margin?

Answer 4

Areas between two crustal plates that are moving past each other in opposite directions or at different speeds.

Question 5

Whats meant by a constructive plate margin?

Answer 5

An area where two tectonic plates are moving away from one another.

Question 6

Whats meant by continental?

Answer 6

Belonging to a continent, eg Africa, Asia, Europe.

Question 7

What is the continental crust?

Answer 7

The surface of the Earth’s crust found underneath large land masses.

Question 8

Whats meant by convection currents?

Answer 8

A movement within the Earth’s mantle caused by the heat of the core.

Question 9

Whats meant by a destructive plate margin?

Answer 9

When two tectonic plates move towards one another. The oceanic crust is forced to sink back into the mantle, whilst the continental crust rises above. Volcanoes and earthquakes are found here.

Question 10

Whats meant by oceanic?

Answer 10

Relating to the ocean.

Question 11

What is the oceanic crust?

Answer 11

The surface of the Earth’s crust found underneath the oceans, forming the ocean floor.

Question 12

What is a plate margin?

Answer 12

The region where two or more tectonic plates meet. It is a zone of intense seismic activity.

Question 13

What is subduction?

Answer 13

When one crustal plate is forced beneath the other.

Question 14

The earth’s surface is made up of two types of crust, what are they?

Answer 14

Oceanic crust - found underneath the oceans. It is denser than continental crust and can be subducted.
Continental crust - found under land masses or continents. It is generally older than oceanic crust and is less often destroyed.

Question 15

Where are earthquakes found?

Answer 15

Earthquakes are found along all types of plate margins .

Question 16

Where are volcanoes occur at constructive and destructive plate margins?

Answer 16

Volcanoes only occur at constructive and destructive plate margins.

Question 17

What is Hawaii?

Answer 17

Hawaii is an arc of volcanic islands, found above a hot spot.

Question 18

Whats the ring of fire?

Answer 18

A lot of volcanic activity occurs in the ‘ring of fire’. The ‘ring of fire’ is a group of volcanoes that are located along the plate margin of the Pacific plate.

Question 19

Which plates are involved in a destructive plate margin?

Answer 19

A destructive plate margin usually involves an oceanic plate and a continental plate. The plates move towards one another and this movement can cause earthquakes.
As the plates collide, the oceanic plate is forced beneath the continental plate. This is known as subduction. This happens because the oceanic plate is denser (heavier) than the continental plate.
When the plate sinks into the mantle it melts to form magma. The pressure of the magma builds up beneath the Earth’s surface. The magma escapes through weaknesses in the rock and rises up through a composite volcano. The volcanic eruptions are often violent, with lots of steam, gas and ash.

Question 20

What is a collision margin?

Answer 20

If two continental plates collide, neither can sink and so the land buckles upwards to form fold mountains. This is called a collision margin. Earthquakes can occur at collision margins.

Question 21

What happens at a constructive plate margin?

Answer 21

At a constructive plate margin the plates move apart from one another. When this happens the magma from the mantle rises up to make (or construct) new land in the form of a shield volcano. The movement of the plates over the mantle can cause earthquakes.

Question 22

What happens at conservative plate margins?

Answer 22

At a conservative plate margin, the plates move past each other or are side by side moving at different speeds. As the plates move, friction occurs and plates become stuck. Pressure builds up because the plates are still trying to move. When the pressure is released, it sends out huge amounts of energy, causing an earthquake. The earthquakes at a conservative plate boundary can be very destructive as they occur close to the Earth’s surface. There are no volcanoes at a conservative plate margin.