Download Plate Movement

Convection and Plate
Movement

Convection is the movement caused within a
fluid by the tendency of hotter, less dense
material to rise, and colder, denser material to
sink under the influence of gravity, which results
in transfer of heat.

Heating of the mantle by the core creates
convection currents in which hot, less dense
mantle material rises, cooling at the crust at
which point it descends.

Mantle convection is responsible for plate
tectonics and continental drift.
https://www.youtube.com/watch?v=0mWQs1_L3fA

Scientists believe that the lithosphere is
broken into 10-12 major plates, plus
many smaller ones.

Plate boundaries are the area where
two plates meet.

Lithospheric plates can be either
continental or oceanic.

Lithospheric plates are always moving at
a rate of 2-20 cm per year.

At plate boundaries plates can collide,
separate, or slide past each other.

Convergent boundaries occur when the
edges of plates move toward each other or
collide.

If the converging plates are equal in density
the boundary will crumble upward and
form mountains.

If one of the plates is more dense than the
other, the denser plate will slide below as
they collide.

When one plate is pushed under another
it is called subduction.

When two oceanic plates collide and
one sinks below, a deep-sea trench is
formed.

The sinking plate is heated causing it to
partially melt, forming volcanoes in the
plate above.

Divergent boundaries occur when the
edges of plates move apart from each
other or separate.

As the plates separate rising magma
cools and forms new seafloor.

As the plates continue to spread a chain
of volcanoes called a mid-ocean ridge
will form.

Transform boundaries occur when the
edges of plates slide past each other.

Lithosphere is neither created nor
destroyed along a transform boundary.

Destructive earthquakes are common
along transform boundaries.