Layers Of The Earth

Last Updated : 04 Mar, 2024

Layers of Earth: The structure of the Earth or the interior of the Earth comprises four separate layers: the inner core, outer core, mantle, and crust. People have only explored the outermost layer, the crust, and haven’t gone inside to see the other layers. Over time, with the Earth gradually cooling, geologists posit that the denser materials descended toward the center, while the lighter ones ascended toward the surface. As a result, the outermost layer comprises heavier rocks and granites, while the innermost layer is mostly nickel and iron.

In this article, we will discuss the interior of the Earth and the different layers of the Earth in detail.

Table of Content

What are the Layers of the Earth?
Crust
Mantle
Outer Core
Inner Core
Innermost Core

What are the Layers of the Earth?

Inside the earth are 3 different layers, including Crust, Mantle, and Core. The outer layer of the earth is the Crust. The mantle is the second layer of our Earth and the center is its deepest layer (the core – is divided into two parts – inner core and outer core).

Also Read: Earth’s Interior: Crust, Mantle and Core

Crust

The crust of Earth is like the shell of a hard-boiled egg. Compared with what is beneath it, it is very thin, cold, and brittle.

The crust is composed of relatively light elements, especially silica, aluminum and oxygen.
It is also extremely variable in its thickness.
It may be as little as 5 kilometers (3.1 miles) thick under the oceans (and Hawaiian Islands).
Under the continents, the crust can be as much as 30 to 70 kilometers (18.6 to 43.5 miles) thick.
It’s a solid rock layer divided into two types:
- The land is covered by continental crust and,
- Oceanic crust covers water
The crust is also broken up into large pieces, with the upper part of the mantle, like the pieces of a huge jigsaw puzzle. These are called tectonic plates.
These tectonic plates move slowly-by just 3 to 5 centimeters (1.2 to 2 inches) per year.
How tectonic plates move is yet to be fully explained. Perhaps it’s caused by heat-driven convection currents in the mantle below.
Others see this as a tug created by slabs of crust of unequal density, which scientists call “slab pull.” Over the course of time the plates will converge, pull apart or slide along one another.
Such actions create most earthquakes and volcanoes.

We can divide the crust into two sub-parts as mentioned below:

Oceanic Crust

The oceanic crust is the outermost layer of the Earth. It present under the oceans which is the part of lithosphere.

The crustal mass beneath the water is about 10 km thick.
In general, it is made up of iron- and magnesium-rich rocks. This is because this layer is overburdened by commonly heavy, inert, thick shakes of “mafic” character.
Virtually all of these mafic rocks are volcanic in origin and are referred to as “basalts.”
The crust is also broken up into large pieces, with the upper part of the mantle, like the pieces of a huge jigsaw puzzle. These are called tectonic plates. These tectonic plates move slowly-by just 3 to 5 centimeters (1.2 to 2 inches) per year.1

Continental Crust

Continental crust is the outermost layer of the Earth which is older than the oceanic crust.

This crustal mass represents the continental layer.
The continental crust is about 30-50 km thick.
It is made up of igneous, metamorphic, and sedimentary rocks.
The oceanic crust is thicker than the continental crust.
The continental crust is made up of lightly shaded rocks.
In fact, these stones are simply improved silicates lighter elements, such as aluminum, potassium, and sodium, placed in the mixture. Therefore this layer is called “SiAl”.

Also Read: Composition of Earth’s Atmosphere

Mantle

The mantle layer is the interior of the earth and present beyond the crust. It is a solid state.

It is almost several times thicker than the external cover.
The thickness varies from 10-200km, and the mantle runs from the discontinuity to 2,900 km.
Abandoning the strong to semi-fluid state. The upper part of the Mantle is the asthenosphere.
When volcanic emissions take place, the central wellspring of magma finds its direction to the surface.
Repetti Discontinuity is the discontinuity between the upper mantle and lower mantle.
The mantle is thicker than the crust. T
The outermost piece of the mantle and outer skin form the lithosphere.
The thickness is almost 2900 kilometers.
It contains around 83 % of the whole volume of the Earth.
It is further divided into two distinct layers, upper mantle and lower mantle.

We can divide the mantle layer into two sub-parts as mentioned below:

Upper Mantle

From start to finish, the upper mantle amounts to some 670 kilometers.
It is a thin, delicate mass. It consists of peridot sites.
The upper mantle rocks contain minerals such as olivine and pyroxene stones. These tuff rocks are less pliant and more delicate because temperatures are cooler and pressures lower.
Iron and magnesium make rocks much better, and they are called “ultramafic” rocks. Because of the presence of iron and magnesium in these stones, their assortment is dull.

Lower Mantle

The Lower Mantle is much thicker and denser.
It lies 670 to 2900 kilometers beneath the surface of the Earth.
This is a hot, plastic layer. Close to its inward limit it is delicate and in an almost fluid condition.

Also Read: Interior of the Earth

Core

The innermost layer of the earth is the core. Here are some details about it.

It stretches around 3,500 km.
The inner core is solid, and the outer core is liquid.
The core is mostly heavy material, chiefly nickel and iron; therefore it is also called the ‘nife” layer.
The focal center has an extremely high temperature and tension. Guttenberg’s Discontinuity divides the core from the mantle.
The core makes up 15 % of the earth’s volume and 32.5 % of the earth’s mass.
The earth’s core is the dense layer at the heart of the earth, with a density of 9.4-14.5g/cm 3.
Earth’s central Core is divided into two layers, Outer Core and Inner Core.

Outer Core

The Outer Core is a hot, fluid layer and the Inner Core is a hot, strong layer.
The outer center is about 2250 km thick.
This outer center supposedly is in a fluid state.
The reason: Given the particular behavior of seismic tremor waves, especially shear body waves or auxiliary waves, there may be such a center in a molten state.
Temperatures in the external center are around 4000-5000^oC.
In the attempt to learn the secrets of Earth’s geology, researchers have discovered the fifth layer of the planet. The earthquake-driven seismic waves

Also Read: Materials of Earth’s Crust : Rocks And Minerals

Inner Core

The inward center is 5150-6370 km from the surface of the earth.
It’s mainly iron and nickel with some light constituents, perhaps sulfur, carbon, oxygen, silicon, and potassium.
The temperature in the inward center is about 5000-60000^oC. Because it’s highly strained, the internal center is strong. This fifth layer is of iron and nickel, the constituents which make up the remainder of the inner core. A team of researchers from the Australian National University gauged the velocities at which these tremors pass through the Earth’s center.
It is the presence of iron and nickel that makes the strength of the internal center.
The middle of the center is so frightfully hot that the strain is relentless to the point that the liquefying point of iron and nickel gets pushed well past those high temperatures.

Also Read: What are the Four Major Domains of the Earth?

Innermost Core

It is the fifth layer of the Earth which is around 2414 km thick. Here are some details.

In the attempt to learn the secrets of Earth’s geology, researchers have discovered the fifth layer of the planet.
The earthquake-driven seismic waves have shed new light on the deepest parts of Earth’s core, the inner core.
This fifth layer is of iron and nickel, the constituents which make up the remainder of the inner core.
A team of researchers from the Australian National University gauged the velocities at which these tremors pass through the Earth’s center.
The team believes that this shows evidence of a distinct layer within Earth, the innermost inner core.
About 20 years ago it was speculated that inside the inner core, the innermost inner core, is an internal metallic ball.

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Four realms of the Earth

Four Major Domains of the Earth

Summary

The Earth is like a big ball with different layers inside. Imagine it’s like an egg – the hard shell is the crust, the white part is the mantle, and the yolk is the core. The crust is like the skin on the egg, it’s thin and covers everything. There are two types of crust: one under the land and another under the oceans. Below the crust, there’s the mantle, which is thicker and kind of like a gooey layer. The core is right at the center, and it has two parts – an outer part that’s liquid and an inner part that’s solid. The core is mostly made of heavy stuff like nickel and iron. Recently, scientists found a super innermost layer within the core, making it five layers in total. It’s like peeling layers off an onion to understand what our Earth is made of.

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