1.4 Earth's Conveyor belt

Question 1

What is the Earth’s structure made up of?

Answer 1

• inner and outer cores
• mantle
• outer crust

Question 2

What is the outer core?

Answer 2

ocean of liquid metal 2,300 thick (created as the Earth rotates and this ‘ocean’ swirls creating a magnetic field

Question 3

How does the Earth cool?

Answer 3

from inside out - liquid outer core is becoming solid and larger (1cm every 1000yrs) as latent heat seeps into mantle

Question 4

What is the Peridoite?

Answer 4

upper mantle which contains magnesium and iron

Question 5

In the asthenosphere what is the closest to melting?

Answer 5

peridoite

Question 6

What happens as you go deeper into the Earth?

Answer 6

pressure and temperature increase to melting point

Question 7

Where does decompression happen?

Answer 7

at a constructive plate boundary

Question 8

How does decompression occur?

Answer 8

pressure decreases the further away from the core, due to the low pressure less heat is needed to melt the mantle so it rises and starts to partially melt

Question 9

Why does magma rise?

Answer 9

little pockets of minerals melt and are squeezed out due to pressure from the crust which forms magma

Question 10

How does a mid-ocean ridge occur?

Answer 10

magma collects in chambers and rises to surfaces in waves as it escapes from developing fractures due to it being less dense than ‘solid mantle’ and erupts at divergent plate boundaries (if in the middle of the ocean get a mid-ocean ridge or if above the ocean get an island)

Question 11

How does the seafloor spread?

Answer 11

as a mid-ocean ridge gets heavier under gravity it slides away (ridge push) which worsens as at the other end of the plate subduction zones are subduction zones where gravity pulls down the plate (slab-pull)

Question 12

What is paelomagnetism?

Answer 12

Earth’s magnetic field reverses roughly every 200,000 years as rocks gain a symmetrical pattern of polarity as they move further away from the crust so the lava on the surface cools meaning the magnetic minerals align in the direct of the Earth’s magnetic field

Question 13

What is formed due to paleomagnetism?

Answer 13

an oceanic crust formed at a mid-ocean ridge that is being pulled away from ridge in two directions by different plates

Question 14

Where is an example of a mid-ocean ridge?

Answer 14

mid-Atlantic - Surtsey in Iceland