how convection currents drive plate tectonic movements

Convection currents occurred in the mantle and these are driven by the heat of
the core. This heat is created due to both the pressure of the overlying
material but also produced by the radioactive decay of uranium etc in the
core and mantle.
· As heat rises from the core it creates convection currents in the liquid outer
core and mantle. These convection currents move the tectonic plates on top of
them.

How do we know that the plates move?
Pangaea…
The continents were once all joined together – Pangea. How do we know this? Identical fossils and rocks have been found in western
Africa and Eastern South America for example.
Today the lithosphere is split into 15 tectonic plates. Where 2 plates meet together = plate boundary.

CONSTRUCTIVE PLATE BOUNDARY

· Where two oceanic plates are moving apart from each other.
· New oceanic crust is forming constantly in the gap created.
· The magma is injected between the two plates. As it cools it forms new oceanic
crust.
· The magma is runny. Shallow sided volcanoes form.
HAZARDS:
Convection currents from the mantle bring magma towards
the surface. Magma is forced
between the plates, cools and
forms new oceanic crust.
5 Small earthquakes are formed by friction as the plates tear apart.
Volcanoes that are not very explosive/dangerous.
Examples are Iceland – the Mid Atlantic Ridge.