Layers Of The Earth

There is more to the Earth than meets the eye. If you study it in detail, you will see that it comprises many layers. Thus, the earth’s interiors continue to hold mysteries. Even though we are exploring other planets and deploying satellites into orbit, most of the inner part of our planet remains off-limit. What we know so far is that the earth consists of four separate layers. As per many geologists, the earth’s heavier and denser materials sank in the centre and the lighter ones rose to the top as it cooled. Thus, let us discuss the layers of the earth in detail.

layers of the earth

Introduction to Layers of The Earth

As you know, there are four layers of the earth. If we rank them in order from exterior to interior, they are the crust, the mantle, the outer core, and the inner core. Similar to all the terrestrial planets, the interior of the earth is also differentiated.

In other words, the internal structure comprises of layers, which are arranged similar to an onion’s skin. You peel one and you’ll find another which is different from each other.

Our modern and scientific understanding of the interior of the earth’s structure is based on inferences that have been made with seismic monitoring help. We measure the sound waves which the earthquakes generate and examine how when they pass through the earth’s different layers, they slow down.

Then, we determine the differences in density and use it with measurements of the gravitational and magnetic fields of the Earth. This helps to determine what layers of the Earth looks like.

Besides, the differences in temperature and pressure are because of the leftover heat from the initial formation, decay of radioactive elements, and freezing of the inner core of the planet.

History of the Study

Ever since ancient times, we humans have wanted to understand the earth’s composition and formation. If we look at the earliest known cases, they were unscientific in nature. In other words, it was taken from creation myths and religious fables that involved God.

However, as the medieval period arrives, a lot of theories started coming up about the Earth’s origin and its composition. The majority of the ancient theories were inclined towards the Flat-Earth view.

Then, in the 6th century, it was speculated to be round and then spherical. During this period only, a theory started emerging saying earth consists of minerals and metals. But, it was only in the 17th century when the understanding of the earth’s structure began to advance.

Finally, in the 19th century, it was determined that within the earth’s liquid core is a solid inner core. Thus, by the latter half of the 20th Century, a comprehensive theory was developed about the structure and dynamics of the Earth.

Different Layers of the Earth

There are four different layers of the earth. They are the inner core, the outer core, the mantle, and finally, the crust. After this, we will take a look at all these four layers in detail and study them thoroughly.

The Inner Core

The inner core is the centre and also the hottest layer of the earth. It is solid and comprises of iron and nickel. Moreover, its temperature is up to 5,500oC. Thus, you can say that it is like the engine room of the Earth because of the immense heat energy it possesses.

The Outer Core

When we talk about the outer core of the earth, we see that it is much like quite hot balls of metals having a temperature around 4000oF to 90000F. Due to the extreme hotness, the metals inside are in the liquid state.

Moreover, the outer core is situated around 1800 miles under the crust and just about 1400 miles thick. It comprises of metals like iron and nickel. Thus, the outer core surrounds the inner core.

Further, the pressure and temperature of the inner core are so high that the metals are squeezed together and not able to move like a liquid. Thus, they vibrate instead of solid.


The widest section of the Earth is the mantle. The thickness is just about 2,900 km. It comprises semi-molten rock which we call magma. The rock in the upper part of the mantle is hard whereas the one in the lower down is softer and starts to melt.

The mantle is situated directly under the Sima. It consists of quite hot and dense rock. It flows like asphalt under heavyweight. This flow is due to the greatest temperature differences from the mantle’s bottom to the top.

In other words, the plates of the Earth move because of the movement of the mantle. The temperature of this varies between 1600 oF at the upper part to 4000 oF near the bottom.


The crust refers to the outer layer where we live on. The thickness of the crust is around 0-60 km. It’s a solid rock layer that divides into two types, continental crust, and oceanic crust.

The continental crust is which covers the land and the oceanic one is which covers the water. Further, the crust is the most widely studied and understood part. All in all, the mantle is hotter and can flow.

The outer and inner core are much hotter with great pressures which one can squeeze into a ball smaller than marble if one can go in the earth’s centre.

FAQ on Layers Of The Earth

Question 1: What do you know about the crust of the earth?

Answer 1: The crust is the outermost layer of the earth. In other words, it is then cooled and hardened part of the planet which ranges in depth from around 5-70 km and it makes up only 1% of the entire volume of the Earth.

Question 2: What is the mantle?

Answer 2: The widest section of the Earth is the mantle. The thickness is just about 2,900 km. It comprises of semi-molten rock which we call magma.

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