What is the Earth made of?*

Nobody knows for sure what is inside the Earth.

Scientists have done a lot of research to learn about the inside of the Earth.

They believe the Earth has three layers.

The top layer is the crust.

Under land, the crust is 40 kilometers thick.

Under the water, the crust is 8 kilometers thick.

Under the crust is the mantle.

The mantle is a layer of hard rock.

Under the mantle, there is a layer of melted metal called the outer core.

It is very hot in the outer core.

Inside the centre of the Earth is the inner core.

The inner core is 6,400 kilometers from the surface of the Earth.

The inner core is a round ball of solid metal.