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CORE (INNER AND THEN OUTER) MANTLE - CRUST
CORE ball of solid iron and nickel
MANTLE Semi-molten rock (which moves very slowly)
CRUST Thin (about 20km) Divided into slabs which are called tectonic plates.
Thicker less dense Thinner more dense
Plate margins/ boundaries are where they meet.
DESTRUCTIVE - moving towards each other. Oceanic plate meets a continental plate, the denser
oceanic plate is submerged beneath the continental plate into the mantle and destroyed. Volcanoes
and ocean trenches form this way. Trenches are very deep sections of the ocean floor where oceanic
plate goes down.
E.g. East coast of Japan
CONSTRUCTIVE - moving away from each other. Magma rises from the mantle to fill the gap made by
the departing plates. It cools to create new crust. Fold Mountains are made this way.
E.g. Mid- Atlantic ridge.
CONSERVATIVE Moving sideways. Same direction but different speeds. Crust isn't created nor
E.g. West coast of USA.