GENERAL TECTONICS

Question 1

What is meant by the term crust?

Answer 1

The crust is the outmost layer of the earth.

Question 2

What is meant by there term plate?

Answer 2

A plate is piece of the earths crust.

Question 3

What is meant by the term plate margin?

Answer 3

A plate margin is where two plate meet.

Question 4

What is meant by the term mantle?

Answer 4

The mantle is the layer of the earth that is below the crust and it is made up of semi molten rock.

Question 5

Describe what is happening at a conservative plate margin.

Answer 5

The two plates are moving vertically past each other in the same direction.

Question 6

The San Andreas fault is an example of what type of plate margin?

Answer 6

It is an example of a conservative plate margin.

Question 7

Describe three difference between oceanic and continental crust.

Answer 7

Oceanic crust is denser, thinner and younger than continental crust.

Question 8

What is meant by the term subduction.

Answer 8

It is where an oceanic crust dives downwards into the mantle because it has meet another plate.

Question 9

Describe why the island of Iceland is becoming wider?

Answer 9

Because it is formed on a constructive plate margin. As the plates move apart vertical weaknesses in the crust are formed. Magma then rises along these weaknesses to form new land.

Question 10

Explain why are the plates at a constructive plate margin moving apart?

Answer 10

This is because the margin is above a rising convection current that diverges when it hits the bottom of the crust. This pulls the two plates apart.

Question 11

Define the term collision plate margin.

Answer 11

It is where two continental plates moving in different direction meet.

Question 12

What geographical features are formed at collision plate margins.

Answer 12

The feature that is formed are young fold mountains such as the Himalayas.

Question 13

What type of plate margin runs along the west coast of South America.

Answer 13

A destructive plate margin.

Question 14

What type of plate margin runs north to south down the centre of the Atlantic Ocean.

Answer 14

A constructive plate margin.

Question 15

Explain why convection currents develop in the mantle.

Answer 15

They develop because of localised radio active decay in the upper core. This process produce heat which warms the rock of the overlying mantle.

Question 16

Explain why oceanic crust subducts under continental crust.

Answer 16

It subducts because it is denser than the continental crust.

Question 17

Briefly explain why fold mountains are formed.

Answer 17

They are formed because continental crust is of the same density. Therefore when two continental plates collide one can not subduct underneath the other.

Question 18

Explain why the crust of a subducting plate melts when in drops into the mantle.

Answer 18

It melts because the pressure increases as the crust drops into the mantle.

Question 19

What type of crust is 25 to 100 km thick and mostly made of granite.

Answer 19

Continental crust.

Question 20

What type of crust is 5 to 10 km thick and mostly made of basalt rocks.

Answer 20

Oceanic crust.

Question 21

At what type of plate margin is crust destroyed.

Answer 21

At a destructive margin.

Question 22

What type of volcanoes are mainly found on constructive plate margins.

Answer 22

Shield volcanoes.

Question 23

How fast in millimetres is the Mid Atlantic Ridge moving apart.

Answer 23

It is moving apart at between 20 to 40 mm a year.