we know there are three types of rocks: fiery, metamorphic and sedimentary. Therefore, they are constantly changing their characteristics, changing from one type to another, in a cyclical process called rock cycle (see diagram below).
1st transformation of igneous rocks into sedimentary rocks
As it is a closed cycle, it is not possible to say where its beginning is and where its end is. However, to fully understand the process, let's consider the beginning of the cycle in the transformation of Igneous Rocks.
As the earth moves, many igneous rocks that form many kilometers below the surface end up emerging over millions of years. These rocks end up suffering the action of external agents, such as water, wind, exposure to the sun and rain, among others. With that, the rock changes its characteristics.
This process of soil transformation by external agents is called weathering and your result is the sedimentary rocks. They form when sediments generated by weathering are deposited on the bottom of rivers, lakes and coalesce.
2nd transformation of sedimentary into metamorphic rocks
Over time, the layers of the earth overlap and these sedimentary rocks accumulate to ever greater depths. As a result, they begin to suffer from the pressure of the earth and its extreme internal heat, becoming harder and becoming called metamorphic rocks. The process of heating and hardening the rocks is called metamorphism.
3rd transformation of metamorphic into igneous rocks
As a continuation of this process, metamorphic rocks can suffer even more from the heat and pressure of the earth, such that they can begin to melt, forming lavas. With the hardening of these lavas, we have again the formation of igneous rocks. The melting process of rocks is called Fusion.
4th direct transformations
It is also possible that an igneous rock suffers from metamorphism again and becomes metamorphic again. Just as it is also possible that metamorphic rocks, instead of heating up even more, appear on the surface, suffering the actions of weathering and transforming into sedimentary rocks.
It is just not possible for sedimentary rocks to turn directly into igneous ones, because even if they heat up a lot, first they become metamorphic and then they turn into fiery.
By Rodolfo Alves Pena
Graduated in Geography
Source: Brazil School - https://brasilescola.uol.com.br/geografia/ciclo-das-rochas.htm
