THE Earth's crust it is the surface layer of the Earth, that which manifests itself externally and which is composed of rocks and minerals. Another possible definition for the Earth's crust is to consider it as the solid layer of the planet, although many geologists believe that the portion of the inner core is also solidified.
There are two different ways of classifying the Earth's crust, one considers variations in the vertical plane and the other values differences in the horizontal plane.
The first classification divides it into two sublayers: a Sima and the Sial, which receive these names on the basis of their mineralogical compositions. The sima layer is mostly composed of YesLycian and Badgneiss, being constituted by predominantly basaltic rocks and composing the lower portion of the crust. The sial layer is mainly composed of YesLycian and Aluminium, consisting mostly of granitic, basaltic and sedimentary rocks.
The second classification divides the crust into continental, with thickness ranging between 20 km and 70 km, and
oceanic, with thickness between 5 km and 15 km. The continents differ from the oceans by their constitution, the first ones have a felsic composition, and the second ones, a mafic one.The earth's crust is composed, as we have already emphasized, of rocks and minerals. What differentiates these two terms is that rocks are composed of minerals or aggregates of these. Thus, while minerals are formed by a single chemical compound and generally have a more homogeneous appearance, the rocks show a greater plurality, with a generally more appearance. heterogeneous.
Furthermore, it is important to emphasize that the Earth's crust does not extend continuously, that is, without interruptions throughout the planet. It is fragmented into different parts, which are always moving, bumping and interacting with each other, these are the so-called Tectonic plates, which are responsible for the displacement of continents, the formation of mountains and faults, in addition to being one of the elements responsible for earthquakes, tsunamis and volcanism.
By Me. Rodolfo Alves Pena
Source: Brazil School - https://brasilescola.uol.com.br/o-que-e/geografia/o-que-e-crosta-terrestre.htm
