Plate Tectonics

Question 1

Describe the content of the earth.

Answer 1

Question 2

What is the lithosphere?

Answer 2

The rigid top of the mantle and the crust make up the lithosphere.

Question 3

What are the 2 types of crust?

Answer 3

Continental and oceanic.

Question 4

Describe the continental crust.

Answer 4

Thicker and less dense.

Question 5

Describe the oceanic crust.

Answer 5

Thinner and more dense.

Question 6

What is a plate boundary?

Answer 6

Where tectonic plates meet. Can also be called plate margins.

Question 7

What are convection currents in plate tectonics?

Answer 7

Mantle is hottest close to the core, lower parts of the asthenosphere heat and rise, as the move up they cool down and become more dense and slowly sink, creating a circular movement called a convection current which creates drag on the base of a tectonic plate causing it to move.

Question 8

Describe slab pull.

Answer 8

Occurs at destructive plate margins when the denser crust is forced under less dense crust.

Question 9

Describe ridge push.

Answer 9

At constructive plate margins.
Magma rises to the surface = new crust forms
New crust heats surrounding rocks= expanding slope.
New crust cools and becomes dense
Gravity= new rocks move downslope away from the plate margin putting pressure on the tectonic plate
=move apart.

Question 10

What is ridge push also known as?

Answer 10

Gravitational sliding.

Question 11

What is sea floor spreading?

Answer 11

Tectonic plates diverge= magma rises up to fill gap and cools to form new crust. Over time new crust is dragged apart and process repeats.
=plate margin on sea floor gets wider
Creating structures like mid-ocean ridges

Question 12

Define the asthenosphere.

Answer 12

The semi-molten part of the mantle.
Upper mantle.

Question 13

What is a constructive plate margin?

Answer 13

When plates move apart (diverge).

Question 14

How is an earthquake caused?

Answer 14

Mantles constantly moving at different speeds causing pressure to build and eventually crack making a fault line and causing an earth quake.

Question 15

What landforms are created at a constructive margin?

Answer 15

Ocean ridges
Rift valleys.

Question 16

What is an ocean ridge and how is it formed?

Answer 16

Where diverging plates are under water forming an ocean ridge. Often underwater volcanoes erupt along the ridges and build up above sea level.

Question 17

Give an example of a mid ocean ridge.

Answer 17

Mid-Atlantic ridge is where the Eurasian plate and the North American plate are moving apart.
Volcanoes that formed Iceland are found in this rift.

Question 18

Describe a rift valley and how they are formed.

Answer 18

Plates diverging beneath land, rising magma causes the continental crust to fracture forming fault lines.
When the plates move apart the crust between drops down to form a rift valley.
Volcanoes can be found in rift valleys.

Question 19

Give an example of a rift valley.

Answer 19

East African rift system as the Nubian and Somalian plates are diverging.
Volcanoes such as Kilimanjaro is found in the rift.

Question 20

Describe what happens at a destructive margin.

Answer 20

When two plates move towards each other (converging).

Question 21

What happens when oceanic and continental crusts converge?

Answer 21

The denser oceanic crust is forced under the less dense continental crust forming a deep sea trench.
Fold mountains may also form as sediment is accumulated on the continental crust.
The oceanic crust is heated by magma and the top of the mantle to form magma which rises above the continental crust to the surface forming a volcano.
If the plates get stuck it can cause pressure to build up which will eventually jerk causing an earthquake.

Question 22

What happens when 2 oceanic plates meet?

Answer 22

The denser of the two will be sub-ducted forming a deep sea trench and triggering earthquakes and volcanic eruptions.

Question 23

What is formed when a volcanic eruption occurs underwater?

Answer 23

Island arcs, a cluster of island sitting in a curved line are formed.

Question 24

What happens when two continental plates meet?

Answer 24

Neither is subducted but pressure builds up and causes earthquakes.
Fold mountains form.

Question 25

What is a conservative plate margin?

Answer 25

When plates move past each other.

Question 26

How do earthquakes occur at conservative plate boundaries?
Give an example.

Answer 26

The two plates get locked together and pressure builds up and eventually jerk past each other releasing the energy in an earthquake.
Eg: Pacific and North American plates caused San Andreas fault.

Question 27

What is a magma plume and how do they form volcanoes?

Answer 27

A vertical column of extra hot magma which forms volcanoes above them. Magma plume stays stationary but crust moves forming new volcanoes but leaving a chain of volcanoes.
Eg: Hawaii.

Question 28

Give an example of a conservative plate boundary.

Answer 28

Pacific and North American plates caused San Andreas fault.