We will explore these layers beginning with the innermost layer and moving out toward Earth's surface.
The inner core: This layer is found at the very center of the Earth. It is composed mostly of metals such as iron and nickel. The temperature of the inner core is believed to be about 5,500 degrees Celsius. Despite the extreme temperature, the inner core is believed to be solid due to the great pressure at the center of the Earth.
The outer core: The inner core is surrounded by the outer core. The temperature in the outer core is believed to be higher than 4000 degrees Celsius. Like the inner core, the outer core is made up of metals such as nickel and iron. However, the outer core is believed to be liquid because the pressure is not as great as in the inner core.
The mantle: Surrounding the outer core is a layer known as the mantle. Most of the material which makes up our planet is found in this layer. The mantle is made up of rock. It is divided into two layers; the lower mantle and upper mantle. The temperature in the mantle is believed to be as high as 3800 degrees Celsius near the outer core. The temperature is so high that much of the rock which makes up the mantle is in a semi-molten state.
The crust: This is the outermost layer of the Earth and also the thinnest. It is composed mainly of solid rock. There are two types of crust. The crust which is found below our oceans is called oceanic crust. It is also called sima since it is made up largely of silica and magnesium. Oceanic crust is only about 6 to 10 kilometers thick. Continents are found where continental crust lies above oceanic crust. Continental crust is thicker than oceanic crust. It can be up to 70 kilometers thick. Continental crust is also called sial as it is made up mostly of silica and aluminium.
The video below shows the structure of the Earth.
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