Our changing planet

Structure of the earth

at the surface is a thin, solid crust

the mantle is under the crust and is about 3000km thick

it goes almost halfway to the centre of the earth

the core is about half the diameter of the earth

it has high proportion of the magnetic metals iron and nickel

it has a liquid outer part and a solid inner part

the atmosphere surrounds the Earth

The restless Earth

tectonic plates move a few centimetres a year because of convection currents in the mantle beneath them

the convection currents are are caused by energy released by the decay of radioactive elements heating up the mantle

Alfred Wegener put the idea forward of continental drift in 1915

scientists didnt believe him they believed the Earth was shrinking as it cooled

in the 1960s scientists found new evidence and the theory of plate tectonics was developed

The Earth's…