Layers of the Earth

Did you know the Earth is like an onion? It has layers!

Overview

Scientific evidence indicates that Earth is composed of four layers. These layers are concentric, meaning they are circles that share the same center, with the larger circles or layers completely surrounding the smaller ones. The four layers, working from the surface of the Earth to the center are: the crust, mantle, outer core, and inner core. Take a look below to learn more about each layer.

The Crust

The crust is the outermost layer of the Earth. This layer is where all life occurs. The crust is made up of a variety of the three types of rocks (igneous, sedimentary, metamorphic) and is split into large pieces called tectonic plates. There are 15 major tectonic plates and more than 15 small ones that help to make up the Earth's surface. The crust is the thinnest of Earth's four layers, measuring only 40km (25 miles) on average. There are two different types of crust: oceanic and continental.

The Mantle

The mantle is the second of the Earth's four layers, lying between the crust and the inner core. The mantle consists of hot, semi-solid rock and is the thickest of Earth's layers at about 2,900km (1,802 miles) thick. Like the Earth, the mantle is also divided into 2 main layers: lithosphere and asthenosphere.


Lithosphere - thin, outermost shell of the mantle, similar to the crust, "floats" on the asthenosphere

Asthenosphere - softer, semi-solid layer of the mantle that is constantly moving slowly, this motion is the force behind plate tectonics which creates continental drift, earthquakes, volcanoes, mountains, and trenches.

The Outer Core

The outer core is the third of Earth's four layers, lying between the mantle and inner core. The outer core is composed of a metallic alloy made of liquid iron and nickel. Scientists believe that it is this liquid outer core that controls Earth's magnetic field. This layer is the second largest and is approximately 2,300 km (1,430 miles) thick.

The Inner Core

The inner core is the innermost layer of the Earth. It is a solid ball composed of mainly iron. Although the iron is extremely hot (5,000 - 7,000 degrees Celsius) the immense pressure from the rest of the planet prevents the iron from melting, giving Earth its solid, metal core. The inner core is the second smallest layer at approximately 1,200 km (750 miles) thick. This is the layer that scientists believe gives Earth its magnetic field.

Use this Rap to Remember the Layers of the Earth!

Mr. Lee - Layers of the Earth rap

Check Out this Informative Video about Earth's Layers!

Down To The Earth's Core HD)