The Earth's internal structure is segmented into layers and each of these parts has some particularities in terms of composition, pressure and state.
The planet's surface is part of the thinnest layer, the Crust, and is the only one known to humans. This is where the tectonic plates are located, “floating” on the underlying fluid layer, the Mantle.
More specifically, the tectonic plates form the lithosphere, composed of the crust and part of the mantle. Below is located the asthenosphere, belonging to the mantle.
The Earth's Mantle is composed of two parts: upper and lower mantle. Just below the Mantle is the Nucleus.
The Core is the layer that is in the center of the planet, it is also subdivided into two parts: outer and inner core.
Between the layers there are two boundaries named after the seismologists who discovered them. They are discontinuities that have different characteristics in relation to the two underlying layers.
These boundaries are called:
- Gutemberg Discontinuity (Between the Core and the Mantle);
- Mohovicic discontinuity (between the Mantle and the Crust).
What are the layers of the Earth and how are they organized?
The Earth's layers represent the division between its internal structure and each has its own characteristics and subdivisions.
The terrestrial radius is approximately 6371 km. That is, the sum of the thickness of its inner layers gives this result and is distributed between the Crust (5-70 km), the Mantle (approx. 2900 km) and the Core (approx. 3400 km radius).
Research carried out proves that the deeper the greater the temperature and pressure. The temperature of the Earth's core must exceed 5500 °C and the approximate pressure is 1.3 million atmospheres.
Studies on the Earth's internal structure are carried out using a measuring instrument called a seismograph. Seismographs capture all the internal movements of the planet and, through various calculations, scientists arrive at certain certainties.
Through the use of seismographs it is possible to reach conclusions about the thickness and composition of the Earth's layers.
Temperature is calculated from other scientific experiments that test the behavior of various elements under extreme conditions of temperature and pressure.
Crust
The Crust is the Earth's surface layer. It is the thinnest layer of the planet's structure, with an average thickness that varies between 5 km in the deepest regions of the oceans and 70 km in the continents.
The Earth's crust is basically composed of Silicon and Aluminum on the continents and Silicon and Magnesium on the ocean floor. Hence, the nomenclatures SIAL (Silicon and Aluminum) and SIMA (Silicon and Magnesium) to refer to these portions of the Crust.
It is in the Earth's crust that all known life on the planet is located. Life inside the Earth is unlikely, living organisms would not withstand such high temperatures.
The deepest drilling ever carried out was the Kola Super-Deep Well in the former Soviet Union. In 1989, the well reached the 12,262 meter mark with an interior temperature of 180 °C. Even so, drilling remained in the planet's superficial layer, not reaching the Mantle.
See too: Earth's crust.
cloak
The Earth's Mantle is the intermediate layer, is below the Crust and above the Core. Its thickness is about 2900 km. The Mantle is responsible for about 85% of the planet's mass.
It is commonly divided into two parts: Upper Mantle, closer to the surface and Lower Cloak, closer to the core.
Upper Mantle
Due to the high temperatures, the Upper Mantle is in a state of magma, molten rock with a paste-like appearance.
Lower Cloak
In the Lower Mantle, due to the high pressure, the rocks are in a solid state, although with higher temperatures compared to the upper part. The temperature in the deepest areas of the Lower Mantle reaches about 3000 °C.
Core
The Core is the innermost part of the Earth's structure. It is also called NIFE because it is composed of Nickel and Iron.
Like Mantle, the Core is subdivided into two parts: Outer Core (liquid) and Inner Core (solid).
External Nucleus
The outer part of the Earth's Core is composed of liquid nickel and iron and is approximately 2200 km thick.
The temperature of the Outer Core varies between 4000 °C and 5000 °C.
Internal Nucleus
The Inner Core is the deepest part of the Earth's internal structure, has a radius of 1200 km and is located about 5500 km deep in relation to the surface.
The temperature inside the Core is close to 6000 °C, a temperature very similar to that of the Sun.
Its interior is basically composed of iron in solid state, due to the pressure, 1 million times higher than at sea level.
Studies show that the Inner Core rotates faster than the Earth's rotational motion. This is only possible by being immersed in a liquid medium.
What are the Gutemberg and Mohovicic discontinuities?
The Gutemberg Discontinuity is a small stretch that separates the Outer Nucleus from the Inferior Mantle. It was discovered by German seismologists Beno Gutemberg and Emil Wiechert.
This discovery resulted from the proof of the change in wavelength in this medium.
The same was detected by the Yugoslav geophysicist Andrija Mohorovicic in relation to the boundary between Earth's Crota and the Upper Mantle.
Interested? See too:
- Types of Rocks
- Tectonic plates
- Earth Layers Exercises
