Layers of the Earth (Meaning and Explanation)

We explain what the layers of the Earth are and their characteristics. Furthermore, the Mohorovicic and Gutenberg discontinuities.

layers of the earth crust mantle core — The layers of the earth are the crust, mantle and core.

What are the layers of the Earth?

Planet Earth is a spheroid planet with an equatorial diameter of 12,742 kilometers, with a slight flattening at the poles. Humanity, along with other forms of life, live on its surface (the biosphere). But inside, The planet is made up of a set of concentric layers of different composition and dynamics.

The set of these layers makes up the geosphere. As with other rocky planets, the layers of the Earth become more and more dense as we move towards its center, where the planetary core is located. On the other hand, the deeper we go, the more heat there will be, and the closer we will get to the geological past, that is, to the traces of the planet's very formation.

The layers of the Earth, then, There are three: crust, mantle and core each of which comprises various intermediate strata and has certain characteristics, which we will see separately below.

Earth's Crust

layers of the earth crust — All living beings live in the earth's crust.

It is the most superficial layer of the planet, on which living beings live even those that inhabit the depths of the soil.

The deepest hole that humans have ever dug, called the Kola Superdeep Well (former Soviet Union), is 12,262 meters deep, and is within the range of the Earth's crust. Himself It extends from the surface itself (0 km) to a depth of 35 kilometers.

Mohorovicic discontinuity

At an average depth of 35 kilometers (70 in the continents and 10 in the oceans) is the so-called Mohorovicic Discontinuity or “Moho”, a transition zone between the Earth's crust and the mantle. It serves as a transition between the less dense crust and the denser iron-magnesium silicate rocks that begin the mantle.

Lithosphere

The lithosphere is another name given to the upper layer of the Earth, ranging from 0 to 100 kilometers deep, that is, It covers the entire Earth's crust and the first kilometers of the upper mantle or the asthenosphere.

Its name literally means “stone sphere.” AND It is fragmented into a set of tectonic plates on which the crust rests on whose edges geological accidents known as faults or magmatism occur, giving rise to mountains and depressions (orogenesis) by folding.

The lithosphere can be continental or oceanic depending on what type of crust is above it, being thicker in the first case and thinner in the second.

Asthenosphere

Located below the lithosphere, between 100 and 400 kilometers deep, it is located the upper zone of the mantle known as asthenosphere. It is composed of highly ductile silicate materials, either in a solid state or semi-molten due to pressure and high temperatures.

This layer allows the movement of tectonic layers over it thus allowing continental drift. As we approach its lower edge, however, the asthenosphere loses its properties and quickly becomes rigid.

You may be interested: Continental Regions

The earth's mantle

The layer that follows the crust, strictly speaking, is the Earth's mantle, which also It is the largest stratum on the planet, covering 84% of the Earth. It extends from 35 kilometers deep to 2890, where the Earth's core begins.

It becomes progressively hotter as you move towards the core. Oscillates between temperatures of 600 °C to 3500 °C between its upper strip and the vicinity of the core.

The mantle contains rocks in a viscous paste state due to the high temperatures and enormous pressure, although contrary to what one would think, as one advances towards the core the rocks tend to be more and more solid, due to the gigantic pressures that force them to occupy the minimum possible space.

The command is subdivided into two regions:

Upper mantle From the “Moho” to 665 kilometers deep, where peridotitic, ultrabasic rocks predominate, composed mainly of magnesium olivine and pyroxene (80% and 20% respectively).
Lower mantle Extending from 665 kilometers deep to the so-called Gutenberg discontinuity at about 2900 kilometers deep, it is a very solid zone with low plasticity, of much higher density, despite its temperatures between 1000 and 3000 °C. It is thought that it could hold more iron than the upper layers, given its proximity to the core.

The Gutenberg Discontinuity

layers of the earth gutenberg discontinuity — In the Gutenberg discontinuity, the magnetosphere is born that creates the northern lights.

Between the Earth's mantle and the planet's core there is another discontinuity, located almost three thousand kilometers deep. Its name pays tribute to its discoverer, the German geologist Beno Gutenberg, who discovered its existence in 1914.

It is the region where the electromagnetic waves that generate the magnetosphere are born terrestrial, thanks to the friction of the external core, composed of ferromagnetic metals, and the mantle.

You may be interested: Continental Drift

The earth's core

The innermost area of all the Earth's layers is the core. It is located almost 3,000 kilometers deep and extends to the center same of the planet.

It is the densest region on the planet which is saying something, since Earth is the densest planet in the Solar System (5515 kg/m³ on average). This means that the pressure in the core is millions of times that of the surface, and that Its temperatures reach up to 6700 °C.

The core is made up of two different parts:

The outer core It reaches up to 3,400 km in depth and is semi-solid in nature, probably composed of a mixture of iron, nickel and traces of other elements such as oxygen and sulfur.
The inner core Which is a solid sphere with a radius of 1220 km, composed mostly of iron, although with a minority presence of nickel and other heavy elements, such as mercury, gold, cesium and titanium. It is possible that the inner core rotates faster than the rest of the layers, and that its gradual cooling generates part of the planet's enormous amount of internal heat.

Continue with: Earth Rotation