Layers of the Earth: Crust, Mantle, Outer Core and Inner Core

0:00What is inside our planet, under the ground we stand on?

0:04On average, it is 6,371 kilometres from Earth's surface to its centre.

0:12Imagine cutting Earth open. Inside are four main layers, drawn here to scale.

0:19The outer layer is the crust, the solid rock of the land and the ocean floor.

0:24Drawn to scale, the crust would be thinner than this line, so let's zoom in.

0:31Under the oceans, the crust is only about 5 to 10 kilometres thick.

0:36Under the continents it is about 30 to 70 kilometres thick, thickest under mountains.

0:44The crust and the rigid top of the mantle below it together make up the lithosphere.

0:51The lithosphere is broken into large pieces called tectonic plates.

0:56Below the crust is the mantle, the thickest layer, down to about 2,900 kilometres.

1:03The mantle is not a sea of lava. It is almost all solid rock.

1:09But it is so hot that it flows very slowly, a few centimetres a year.

1:16The outer core goes down to about 5,150 kilometres. It is liquid iron and nickel.

1:25At the centre is the inner core, a solid ball of iron and nickel.

1:30It is about as hot as the surface of the Sun.

1:34Huge pressure from all the layers above keeps it from melting.

1:39So from the outside in: the crust, the mantle, the liquid outer core and the solid inner core.