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Earth's crust and the solid rocky and brittle upper mantle are known as the lithosphere. This is broken up into a number of different sections or pieces known as tectonic plates.

Underlying the lithosphere is the asthenosphere made up of the softer mantle rocks that behave as a viscous fluid (like an extremely thick treacle).

Heat within the earth causes the asthenosphere to convect. This movement causes the overlying lithosphere to move as well.

Also where mantle material rises to shallower depths it undergoes a process known as decompression melting. This causes the formation of magma which rises to Earth's surface. This hot (and therefore lower density) material forms a raised area in the Earth's crust known as a mid-ocean-ridge. Gravity acts to try and pull the buoyant hot new crust back down and this force is transferred horizontally through the crust in a process known as "Ridge Push". As the material cools and travels away from the mid-ocean -ridge it sinks slightly back down due to it's increased density and so lower buoyancy.

Ultimately this dense oceanic crust may meet a tectonic plate composed of continental crust which has a lower density and is more buoyant than the oceanic crust. Because of this the denser oceanic crust is forced down below the continental crust. This process is known as subduction. The force of gravity acting on the subducting slab is transferred into the rest of the slab acting to pull it towards the subduction zone. This process is known as "slab pull".

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Related Questions

Why the crust move?

the earth's crust is made up of 7 rigid,irregularly shaped plates(slabs). these are called lithospheric plates. these plates move because of the molten magma under the earth's crust which move in a circular motion that's why the earth's crust moves and earthquakes occurs


When earthquake happen when these sections of earth crust move?

earthquakes happen when these sections of earths crust move


Is the Earth's crust is in motion?

Convection currents of heat underneath the earth's crust in the mantle (magma) cause the tectonic plates of the earth's crust to move.


Why is the Earth's crust in constant in motion?

Convection currents of heat underneath the earth's crust in the mantle (magma) cause the tectonic plates of the earth's crust to move.


Why is earth's crust in constant motion?

Convection currents of heat underneath the earth's crust in the mantle (magma) cause the tectonic plates of the earth's crust to move.


How does the convection currents cause te crust of the Earth to move?

Because the convection currents involve the Earth's crust.


What explains the movement of the Earth?

The earth's crust moves because the earth has tectonic plates that move because the magma under the earth's surface is constantly boiling. Since the water moves, it causes the earth's crust to move.


A place where pieces of earth's crust move is the?

Lithosphere.


What is a break in earth's crust along which portions of earth's crust move relative to one another called?

They are called fault lines.


What makes the earth crust move?

The vibration of the techtonic plates. :)


What earthquakes happen when these sections of earth's crust move?

a salami.


What is a break in earth's crust which rocks move is called what?

A fault.