Restless Earth (1) (explain a plume (1) - Parts of convection cells where…
Restless Earth (1)
layer of gases which make up the air around us.
oxygen, CO2 for plant growth, greenhouse effect to keep warm and weather and climate.
layer of water on earth's crust.
water for animal and plant life and the water cycle.
very thin layer of living things.
plants and animals provide us with food and many living things make medicines and fuels.
the rocks in the earths crust and deeper into the earth.
magnetic field and fuels.
Give 2 reasons why tectonic plates move
They move because they are composed of the crust and upper mantle rock which is lighter then the more dense mantle.
Rising and falling convection currents in the mantle cause slow movements in the plate as the heat rises and falls.
explain a plume
- Parts of convection cells where heat moves towards the surface.
- the mantle is less dense in a plume and it brings magma to the surface.
- If magma breaks through crust, it erupts as lava.
How do plumes form a constructive plate boundary and a hot spot?
If a plume rises like long sheets of heat they form a constructive plate boundary at the surface.
plumes like columns of heat from hot spots. Hot spots can be in the middle of a tectonic plate.
What is a tectonic plate?
Earths lithosphere is split into 15 large plates and 20 small ones.
The plates move very slowly on the asthenosphere.
Where the two plates meet there is a plate boundary.
What is a conservative plate boundary
as plates slide past, friction between them causes earthquakes.
these are rare but very destructive
What is a Constructive Plate boundary
As plates move apart, magma rises up though the gap. It forms lava flows and shallow sided volcanoes.
Small earthquakes are caused as the plates tear apart.