Layers of the Earth: Inner and Outer Core, Mantle and Crust

Earth consists of four separate layers. This is part of Earth that we can only see superficially. If you end up grabbing earth and cutting it in the middle, you will see different layers. The inside of reality still holds back quite a few secrets from us. Similar to all other terrestrial planets, the interior of the earth is also differentiated. Here, we will study the layers of the Earth in detail along with some important questions.

The layers of earth can be compared to that of an onion skin. If you peel it, you notice that it is different from each other. Most of the geologists, after years of research, firmly believe that as the Earth cooled, the heavier and the denser material sank into the center and the lighter ones rose towards the top. As a result, the outermost layer is composed of the lightest elements, such as rocks and granites, while the innermost layer is composed of nickel and iron.

Different Layers of Earth

According to most of the geologists, as the Earth cooled, the heavier and the denser material sank into the centre, and the lighter ones rose towards the top. This is the reason why the outermost layer is made of the lightest materials such as rocks and granites while the innermost layer comprises nickel and iron. Earth consists of four separate layers, which are: the inner core, the outer core, mantle, and crust make up the four layers of earth.

The Inner Core

It is at the center and by far the hottest layer on earth. This inner core consists of solid and is made up of iron and nickel, having a temperature of 5,550 degrees Celsius. It acts as the engine room for mother earth. The major reason why iron and other heavy metals can withstand such high temperatures is that their liquefying temperatures rise dramatically at the weights present, which range from about 330 to 360 gigapascals. Because the inner core isn't inextricably linked to the Earth's strong mantle, the possibility that it rotates faster or slower than the rest of the planet has long been discussed. Researchers estimate that the inner core pivots at a pace of one degree faster than the surface based on variations in seismic waves as they pass through the core over decades. Later geophysical evaluations estimate the rate of rotation to be between 0.3 and 0.5 degrees per year in relation to the surface.

According to recent discoveries, the solid inner core is made up of layers separated by a shifting zone that is between 250 and 400 kilometers thick. The deepest layer of the core, which contains an inner core, is estimated to be 1,180 km (733 miles) wide in this fresh viewpoint on the inner core, making it not precisely a big percentage of the inner core's measurement. It's also been suggested that, while the core is comprised of iron, whatever remains of the inner core might be in a different crystalline structure.

Furthermore, further investigations have led geologists to believe that the deep within elements are causing the Earth's inner core to grow at a pace of about 1 mm each year. This occurs because the inner core is unable to break down the indistinguishable amount of light components from the outer core.

The Outer Core

This can be compared to a very hot ball of metals. The temperature ranges from 4000-degree Fahrenheit to 9000-degree Fahrenheit. It is exceptional which is why it is all in the liquid state. The outer core is placed at 1800 miles below the crust and is about 1400 miles thick. It is formed of metals like iron and nickel.. The outer core does surround the inner core.

The inner core's pressures and temperatures are so high that the metals are pushed together and unable to flow freely like a liquid, forcing them to vibrate rather than solidify.

Mantle

The Earth's mantle is the widest part of the planet. It has a thickness of 2,900 kilometers. The majority of the mantle is made up of magma, a semi-molten rock. The rock in the top portion of the mantle is hard, but it becomes softer and melts as it descends.

The mantle lies just beneath the Sima. The mantle is made up of extremely hot and thick rock. Under tremendous weight, this layer of rock flows like asphalt. The largest temperature variations from the bottom to the top of the mantle create this flow. The movement of the Earth's plates is caused by the movement of the mantle. Its temperature varies from 1600°F near the top to 4000°F near the bottom.

Crust

The crust is the outermost layer of the Earth's surface, where we dwell. The thickness is between 0 to 60 kilometers. It's a solid rock layer that comes in two types:

• The continental crust covers the land
•  the oceanic crust covers the sea.

The crust has been researched and understood the most. The mantle is very hot and can flow. If we can get to the heart of the Earth, we can be squashed into a ball smaller than a marble since the outside and inner cores are considerably hotter with great pressures.

History of the Study

We have always wanted to understand the earth’s composition and formation. Most of the earliest known facts were mostly unscientific in nature. In other words, it has been borrowed from myths and religious stories that mostly involved a supernatural force.

During the period of medieval earth, a lot of theories came up regarding the Earth’s origin and its composition. Most of the theories revolved around the earth being flat.

In the 6th century, it was discussed and speculated as to how the earth is ideally round and then spherical. During this period, a theory of earth made rounds wherein it was made up of minerals and metals. Only by the 17th century, did we start understanding earth’s structure.

Finally, in the 19th century, it was confirmed that the earth’s liquid core is a solid inner core. By the end of the 20th century, a theory was established about Earth and its dynamics & structure.

To have a proper understanding of the topic, refer to this video:

Things to Remember

• The very center of the Earth is the core which is mostly iron and nickel. 
• The inner core is the solid which measures 1, 516 miles in diameter.
• The outer core of the Earth is a liquid metal which is also mostly nickel and iron. 
• The outer core is 1,408 miles in diameter.
• The mantle of the Earth is solid rock, however, it is not completely hard. 
• The mantle moves slowly and this movement causes earthquakes and volcanic eruptions.