Unit 1 Restless Earth

Question 1

Describe how convection currents cause plate movements

Answer 1

In the mantle the magma heats up in huge convection currents due to radioactive decay. As the heat rises, it pushes against the plates of the crust causing them to move.

Question 2

Describe the differences between continental and oceanic crust

Answer 2

–Oceanic crust is more dense
–Continental crust is less dense
–Oceanic crust is made out of basalt and has no visible crystals
–Continental crust is made out of granite and has visible crystals
–Oceanic crust is newer compared to to continental crust as it is constantly being destroyed and remade

Question 3

How far are the layers of the earth beneath us?

Answer 3

1. Crust 35 km
2. Upper 700 km Lower 2900 km
3. Core 5270-6370 km

Question 4

What happens at a destructive plate boundary?

Answer 4

The oceanic plate is subducted under the less dense continental plate. Friction causes melting of the oceanic plate and may trigger earthquakes. Magma rises up through cracks and erupts into the surface which creates volcanoes

Question 5

What happens at constructive plate boundaries?

Answer 5

Plates move apart. Volcanoes are formed as magma wells up to fill in the gap. Eventually new crust is formed

Question 6

What happens at a collision plate boundary?

Answer 6

Form mountain ranges e.g. Himalayas. Two continental plates of low density granite collide pushing up mountains

Question 7

What happens at a conservative plate boundary?

Answer 7

Plates slide past each other, friction causes earthquakes. These are rare but destructive as they are shallow (close to the surface)

Question 8

Name the characteristics of shield volcanoes (6)

Answer 8

1. Constructive
2. Lava travels a long distance before cooling to form a shield volcano
3. Thin runny lava
4. Gentle sloping slides and a wide base
5. Erupt frequently but not violently
6. Basaltic magma which is very hot with low silica and gas content

Question 9

Name the characteristics of composite volcanoes

Answer 9

1. Destructive plate boundaries
2. Viscous sticky lava and ash that doesn’t flow very far
3. Steeping slopes and narrow base
4. Andesitic magma which contains silica and gas
5. Erupt infrequently but violently
6. Pyroclastic flows

Question 10

Short term aid- saves lives

Answer 10

1. Provide medicine
2. Food and water
3. Doctors and nurses
4. Emergency transport
5. Find missing people

Question 11

Long term aid- improves loves of people

Answer 11

1. Rebuilds roads
2. Improve education
3. Reconnects electricity
4. Rebuilds homes
5. Repairs broken water pipes

Question 12

Predicting earthquakes (5)

Answer 12

1. Animals move out from an area
2. Increase in gas emissions
3. Soli temperature increases
4. Volcano starts to swell
5. Water in ponds gets warmer

Question 13

MEDC building design

Answer 13

1. Double glazed windows
2. Damper in the roof reduces sway
3. Deeper foundations
4. Gas and water lines reinforced
5. Base idolaters act like shock absorbers