Answer:
A. Density increases
Explanation:
The structure of the earth is divided into several successive differentiated layers, the atmosphere, the earth's crust (continental and oceanic crust), mantle (upper and lower) and the core (inner and outer). As we move through the layers of the earth we see an increase in density, ie the core is the densest part of the earth.
- The continental crust contains mainly granite (75%), its average thickness is 45 km and its average density is 2.8.
- The oceanic crust mainly contains basaltic rocks (rapidly cooled lava), its thickness is about 5 km and its average density is 3.1.
- The upper mantle contains essentially solid rocks such as peridotite (iron silicate and magnesium silicate SiO4, Fe and Mg), its thickness is 665 km and its average density is 4.1.
- The lower mantle contains essentially viscous rocks such as perovskite (CaTiO3 calcium titanate), its average thickness is 2185 km and its average density is 4.6. The cloak is always solid, despite the temperature increases when we plunge into its depths, this is due to the pressure on materials that increases even more strongly.
- The liquid outer core consists essentially of cast iron, because at these depths at which the average temperature is 4000 ° C, it is predominant over pressure, the average density at this location is 11.2.
- The solid inner core called the "seed" is essentially metallic, the seed is an alloy of iron (80%) and nickel (20%). The pressure, which is 3.5 million bars (350 GPa), keeps the material in a solid state despite a temperature of about 6000 ° C. The inner core gradually increases by crystallization of the outer liquid iron core, which cools slowly. The density in the depths of the earth is about 13.
