- What is the earth's crust?
- Characteristics of the earth's crust
- Formation of the earth's crust
- Movement and dynamics of the earth's crust
- Layers of the earth's crust
- Importance of the earth's crust
We explain what the earth's crust is, how it was formed, its layers and other characteristics. Also, oceanic and continental crust.
What is the earth's crust?
The earth's crust is the most superficial layer of the planet Earth. It is the outermost, thinnest and most recent of the layers of the Earth. It is the layer on which we inhabit living beings, even those who go into the deepest soil layers.
The earth's crust forms part, together with the earth's mantle and the earth's core, of the so-called geosphere, which is the solid part of the planet. The crust extends from the surface to an average depth of 35 kilometers. The depth is taken on average as it varies depending on whether it is:
- Oceanic crust. It covers 55% of the planet's surface, located thousands of meters deep under the ocean, and it is thinner than the continental one (with a thickness of 5 km at the ocean floor).
- Continental crust. Heterogeneous in nature, since it is made up of rocks of different origins, the most abundant minerals being quartz, feldspars and micas. Its thickness is much greater, reaching 70 km in mountainous areas.
Earth is the only planet known rock that has a heterogeneous crust from a chemical and physical point of view, since they were produced by different geological processes.
Characteristics of the earth's crust
The earth's crust represents less than 1% of the volume total of the planet. However, it is all that we know directly, since it extends up to 35 kilometers towards the nucleus, of which only 12.2 km were excavated with the deepest well in history, the Kola Superdeep Well (KSDB), the work of the old one Soviet Union.
The crust is the upper part of the lithosphere, along with the upper part of the mantle, above the Mohorovicic discontinuity. Since it is much less dense than the mantle, the crust "floats" above it.
As depth increases, so does the temperature, oscillating between 200 and 400 ° C, at a rate of 30 ° C per kilometer of depth.
The chemical elements most abundant in the composition of the crust are: oxygen (46.6%), silicon (27.7%), aluminum (8.1%), iron (5.0%), calcium (3.6%), sodium (2.8%), potassium (2.6%) and magnesium (1.5%). The rest of the volume of the crust is represented by water and other scarce elements, adding up to less than 1% of its composition.
Formation of the earth's crust
In the geological history of the planet, the first Earth's crust was formed 4.4 to 4.55 billion years ago. Since then its volumes have been increasing with the weather.
As conditions on Earth stabilized and the planet cooled, new layers of crust emerged to occupy a considerable volume 2.5 billion years ago, largely thanks to two major geological events: one 2.5-2.7 billion years ago , and another 1700-1900 million years ago.
However, the earth's crust is constantly forming. To do this, portions of it sink into the mantle (subduction) to merge into the underground liquid magma, while other new portions emerge in the expansion centers of the oceanic crust.
The continental crust has an average age of 2 million years, which makes it much older than the oceanic crust.
Movement and dynamics of the earth's crust
The earth's crust is far from static. The plates that compose it are floating on the mantle, made up of pasty materials subjected to enormous pressures. Therefore, a displacement slow motion of the crust, which is known as tectonic dynamics.
Thus, the different portions of the crust rub against each other and collide, exerting pressure on each other and giving rise to the orogenesis or creation of the moutains, as the bark folds and bulges. In this way the relief depends largely on the movement of the bark.
Similarly, depressions or tectonic faults can also be generated, when one plate submerges below the other, liquefying and increasing the internal pressure of the magma to come out. This is how the volcanoes.
These movements of the earth's crust also give rise to the earthquakes and tremors, since the friction between the tectonic plates it produces seismic waves that are transmitted to the surface, sometimes with devastating effects.
In the same way, they originate the Continental drift, which is the movement of the continental masses over time, from the primitive supercontinents (such as Pangea) to the current setting.
Layers of the earth's crust
The earth's crust is a relatively homogeneous layer, that is, it has no layers or subdivisions. The only way to differentiate it is between the thicker, older and more robust continental crust and the younger, thinner and more mobile oceanic crust.
Importance of the earth's crust
The Earth's crust is a vital area of the planet. For starters, that's where life takes place (biosphere), unique phenomenon of our planet in the Solar system.
Also, at this point, the dry and warm rocks can react with the water and oxygen that are abundant on the surface. New forms of rocks and minerals emerge in the crust that make up the mineral wealth and abundance of our environment.
Furthermore, orogenesis would not be possible without the movements of the crust, nor the complex dynamics of geological changes that this implies, and therefore neither could occur chemical cycles What the one with the water, which requires mountains to flow in rivers to the sea.