Layers of the Earth.
From center to top layer:
The Earth is composed by four main distinct layers. They are, from deepest to shallowest: inner core, outer core, mantle and crust.
The inner core: Is made of a solid metal ball with a radius of 758 miles, it is located to 4,000 to 3,220 miles beneath Earth's surface, being extremely dense (made most of iron and nickel). It's almost as hot as the surface of the sun (9,800° Fahrenheit), and with extremely pressure. Some scientists suggests that exist an inner, inner core (consisting of iron, almost entirely);
The outer core: Also made of iron and nickel, but in liquid form. It's 3,220 to 1,790 miles below the surface. The heat of this layers comes most by the decay of uranium and thorium, that cause turbulent currents in this layer generating electrical currents forming the Earth's magnetic field;
The mantle: It's the thickest layer, starting a 18.6 miles beneath the surface. It is made mostly of iron, silicon and magnesium, being dense with solid and semi-solid consistency. In it's edges the temperature reaches the melting point of rocks, and the outermost zone is relatively cold and rigid;
The crust: It's is a extremely thin layer, cold and brittle compared to the other layers below. It's made of a lot of lighter elements as aluminium, oxygen and silica. The crust is made of a big puzzle of broken parts know as tectonic plates that can move with the time and climate events.