The earth is made of 4 different layers, the Crust, Mantle, Outer Core and Inner Core.
The Crust- This varies in thickness from 60km thick to places where you can see the matle below. Features like Volcanoes and mountians are formed from the crust.
The Mantle- This is the liquidy level below the crust its around 2900km thick. When this liquid is in the earth it is called magma, when above the crust the liquid is called lava.
Outer Core-This is believed to be a liquid around 1,800 to 3,200miles under the surface and around 2,300km thick. It is mostly made of liquid Iron and Nickle.