The movement of the plates -
In the mantle and aesthenosphere, hot temperatures from the earths core and radioactive decay produce convection currents. Heat allows the less dense material to rise, as it rises it looses that source of heat, therefore cooling and displacing the material beneath. The circular cell movement moves the overlying plates.
It does this by a mechinasm called plate drag,when the movement in the aesthenosphere drags the crust with it as it moves.
Another way in which plates are moved is ridge push, this is the upwelling of the magma at plate margins which cause the plates to be pushed apart.
This creates Mid Oceanic ridges, for example the Mid Atlantic ridge.
Key features of Mid Oceanic Ridge.
The Mid Atlantic ridge extends down the Atlantic Ocean for 60,000kms.
It spreads apart at 10-15mm per year, the ridge crest is 3000m above the ocean floor.
However, in the pacific the plates are spreading at 90mm per year, this means there isnt enough time for the volcanoes to significantly build up, meaning the ridge crest is lower and smoother it also has no clear rift valley.
Transform - They occur perpendicular to the ridge, and are caused by different rates…