The earth's relief was formed millions of years ago, in the so-called “Earth's geological past”. The forces acting on the relief can be internal (tectonism, earthquakes and volcanism) and external (weatherness caused by water and wind).
Volcanism, an internal agent of relief transformation, is a phenomenon caused by constant variations in pressure and temperature of the magma present in the Earth's interior. Magma is a liquid/pasty substance (at high temperatures) that forms a rocky structure called a volcano. Volcanic eruptions cause the expulsion of magma from the Earth's interior. This substance, in turn, comes into contact with the cooler surface air and hardens, forming the volcano's conical and pyramidal structure.
Today, Brazil is located in the middle of the South American tectonic plate, in a stable region, and the highest incidence of volcanoes occurs in unstable geological regions, that is, on the edges of the plates. In Brazil there are no active volcanoes, as the Brazilian relief was formed in ancient geological periods, millions of years ago. Thus, the volcanoes that existed here in this period became extinct (not active) and nowadays they do not cause any kind of disturbance like in other areas of the world, where volcanic eruptions generate several losses.
Brazil's extinct volcanoes are now tourist spots marked by beauty. These ancient and very old volcanoes were shaped by the action of time.
There were in Brazil volcanic geological formations in the Mesozoic Era, located where today the states of the Southeast and South regions are located. The volcanic spill originated very fertile lands in these states, as is the case with the “purple earth”, of basaltic origin.
In the Cenozoic Era, in the Tertiary period, oceanic volcanic eruptions originated some islands on the coast, such as Fernando de Noronha, Trindade, São Pedro and São Paulo. There were also volcanic basalt spills in the Amazon region in the geological past of Brazil.
Fernando de Noronha and its terrain (of volcanic origin) already modified
By Suelen Alonso
Master in Geography
Source: Brazil School - https://brasilescola.uol.com.br/brasil/vulcanismo-no-brasil.htm
