Tectonic activity

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Geography- Tectonic Activity

Tectonic Plates:

Centre of Earth is iron and nickel=

core

Next

is semi molten rock = mantle

very

thin about 20km = Crust

Crust

is divided into tectonic plates that float on mantle

Crust made

is up of:

Continental- thicker and less dense

Oceanic- thinner and more dense

Where plates meet are called boundaries or plate margins.

Plate

margins:

Destructive- two plates move towards each other

Denser

oceanic plate subducts under continental plate and it is melted in mantle =

volcanoes.

Constructive- two plates move away from each

other

Magma rises

from mantle and fills gap then cool = new crust.

EG:

Mid-Atlantic Ridge

Conservative- two plates are moving sideways past

each other

Can be moving

in the same direction but at different speeds to each other

No crust is

created or destroyed.

EG: West

Coast of USA