Earth is made up of three layers and each of these has different properties. These are the Crust, the Mantle and the Core. However, these layers are further broken down into sub-layers. The crust is made up of two sub-layers; oceanic crust and continental crust. The mantle is divided into two portions; upper mantle and lower mantle. Upper mantle is further sub-divided into two layers; lithosphere and asthenosphere. The core consists of two regions; outer core and inner core. So let’s have a quick overview of each of these layers in Layers of the Earth for Kids.
Layers Of The Earth For Kids
The Crust: The outer layer (Oceanic crust and Continental crust)
The Mantle: The middle layer (Upper mantle and Lower mantle)
The Core: The inner layer (Outer layer and Inner layer)
- The outer layer of the Earth is called the crust.
- It is a thin layer and it is composed of rocks.
- The crust is further divided into two types: oceanic crust and continental crust.
- The thickness of oceanic crust is almost 7 kilometers.
- It is made up of igneous rock (a type of rock) called Basalt.
- The chemical composition of oceanic crust is all the same i.e. homogeneous.
- The density of the rocks of oceanic crust is about 5.7 g/cm3.
- The age of the rocks of oceanic crust is maximum 180 million years.
- Generally, the thickness of continental crust varies from 35 to 40 kilometers. In rocky regions, however this thickness may extend to more than 70 kilometers.
- Continental crust is made up of many different kinds of rocks.
- The density of the rocks of continental crust is about 2.7 g/cm3.
- The age of few of these rocks is just about 4 billion years.
- It is a solid and rocky layer.
- The mantle layer is so huge that it consists more than 82 percent of the entire volume of the Earth.
- The thickness of the mantle layer is almost 2,900 kilometers.
- The mantle is made up of two portions; upper mantle and lower mantle
The upper mantle starts from the boundary which separates the crust from the mantle and goes deep under the Earth at about 660 kilometers. The upper mantle consists of two parts: Lithosphere and Asthenosphere.
- Lithosphere consists of all the crust and the topmost part of the mantle. So the topmost part of the upper mantle is actually a part of lithosphere.
- Lithosphere is therefore a very hard, rocky covering and it is not very hot as compare to other layers.
- The average thickness of lithosphere is about 100 kilometers. However, under very old parts of the continents, its thickness increases to more than 250 kilometers.
- It is located under the lithosphere.
- It is a soft and very weak layer as compare to others.
- The thickness of asthenosphere goes deep under the Earth at about 350 kilometers.
- At the uppermost part of asthenopshere, the lithosphere is not attached rather it gets separated from the bottom layer.
- The upper mantle ends at about 660 kilometers. Starting from 660 kilometers and extends to a depth of about 2,900 kilometers, lower mantle is located.
- Lower mantle is very deep (2,900 kilometers) and very hard because many layers of rocks above exert great pressure on it.
- Rocks of lower mantle are very hot. They can also move slowly.
- The core is made up of iron and nickel alloys. In addition to these, there are some other elements that react with iron very quickly and develop into different compounds. These small amounts of elements are sulfur, oxygen and silicon.
- There is a great pressure inside the core.
- The core is further divided into two different parts: Outer Core and Inner Core.
The Outer Core
- It is a liquid layer.
- The thickness of outer layer is about 2,270 kilometers.
- The magnetic field of the Earth is produced when the iron metal moves in the outer core. Therefore, this is actually the zone from where magnetic field originates.
The Inner Core
- It has a higher temperature as compare to the outer core.
- The iron exists in solid form in this core region. It is because of the great pressure at the center of the Earth.
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Learn more: Earth Facts For Kids