Meaning of Earth Layers
If we could cut planet Earth in half like a peach, we would see certain similarities between the layers of both: the core would correspond to the core of the planet; the edible part would be equivalent to the mantle ; and the shell would be the crust .
The core is the central and warmest part of the planet, with temperatures ranging from 3000 to 5000 ° C. It can be divided into inner core and outer core.
The inner core corresponds to the part that goes from the center of the planet to approximately 1216 km towards the surface. Despite being an extremely hot region, the inner core is solid, as it is under great pressure. It consists mainly of the metals nickel (Ni) and iron (Fe).
The outer core is the layer that extends from the inner core to 2170 km towards the Earth’s surface. It is also composed of iron and nickel, but in a liquid state. Due to the constant movement of this layer, the Earth’s magnetic field is generated , which acts as a shield against strong solar radiation, being one of the factors that make life on the Earth’s surface possible.
The mantle consists of magma , which is a molten rock material. It lies between the core and the earth’s crust, being divided into two parts: the lower mantle and the upper mantle.
The lower mantle is the layer of the planet that starts from the outer core and extends for 2200 km towards the surface. This portion corresponds to approximately 50% of the mass of the planet Earth. In this region, magma is composed of a great diversity of fused elements, such as silicon (Si), magnesium (Mg), oxygen (O2), iron (Fe), calcium (Ca) and aluminum (Al).
Because it is closer to the core, it reaches higher temperatures, up to 4,000 ° C. As they heat up, the deeper layers of magma tend to move towards the crust, forcing the more superficial layers of magma to move towards the nucleus.
The upper mantle is located above the lower mantle, extending for approximately 640 km to the crust. Between the most superficial part of the upper mantle and the solid surface of the planet is a region of pasty rocks called asthenosphere .
This region allows a large part of the phenomena that occur on the planet’s surface, such as earthquakes , volcanic eruptions and tsunamis. In a volcanic eruption, for example, magma reaches the surface. The solidification of the magma gives rise to the magmatic or igneous rocks . These, in turn, when they wear out over thousands of years, form fragments that, when they accumulate in lower areas of the territory, give rise to another type of rock, the sedimentary ones .
Magmatic or sedimentary rocks, which undergo transformations due to the variation in temperature and pressure, generate metamorphic rocks , that is, which have undergone “metamorphosis”.
The crust is the most superficial layer on the planet, consisting of solid rock. It is relatively narrow when compared to the other layers, reaching a thickness of up to 60 km.
The crust is fragmented into several pieces, called plates, which move in several directions, due to the boundary convection currents. They are responsible for intense seismicity, volcanic activities, formation of elongated mountain ranges and basins in the oceans.
It is distinguished in two structures: continental and oceanic.
The continental crust has a thickness that varies from 20 km to 60 km, forming the continents and the continental shelf, a region of the ocean close to the coastal coasts. It is mainly composed of sedimentary and metamorphic rocks .
The oceanic crust is formed by the ocean floor or ocean floor. Its thickness varies between 5 km and 10 km. It is denser than the continental crust, with basalt as a typical rock, a magmatic rock .