The earth's crust is a very thin layer if we compare it with the mantle and the core of the planet
What is the earth mantle? The Earth's crust is formed by more or less rigid plates that rest or float on a high temperature viscous material, called mantle. Sometimes, these materials come to the surface through erupting volcanoes. In addition, they flow continuously through cracks in ocean ridges to form new crust.
About 3,000 km deep is the Earth's core, an area where metals predominate and that, far from being indifferent, influences life on the planet, since it is considered responsible for the majority of magnetic and electrical phenomena that characterize our planet. The Earth has a magnetic field around it thanks to its core, and that protects us from harmful solar radiation.
The heaviest materials on our planet are located in the mantle and the core of the Earth and constitute the bulk of its mass.
The earth's mantle
The mantle of the Earth is a layer of about 2,900 km thick, consisting of denser rocks, where silicates predominate.
At about 650-670 km deep there is a special acceleration of the seismic waves, which has allowed defining a boundary between the upper and lower mantle. This phenomenon is due to a change in structure, which passes from a plastic medium to a rigid one, where it is possible that the general chemical composition of the entire area is preserved.
The continental crust grew by a chemical differentiation of the upper mantle that began about 3.8 billion years ago. At the base of the upper mantle the density is about 5.5 grams per cubic centimeter.
In the upper area of the earth's mantle there are some convection currents, similar to the water that boils in a pot, moving from the lower, hotter, to the upper, cooler portion. These currents are the engine that moves lithospheric plates.
The Earth's core is a gigantic metallic sphere that has a radius of 3,485 km, that is, a size similar to the planet Mars. The density varies, from about 9 grams per cubic centimeter on the outer edge to 12 on the inner part. The Earth's core consists mainly of iron and nickel, with aggregates of copper, oxygen and sulfur.
He external nucleus It is liquid, with a radius of 2,300 km. The difference with the inner core is manifested by a sharp increase in the velocity of the "P" seismic waves at a depth between 5,000 and 5,200 km.
He inner core It has a radius of 1,220 km. It is believed to be solid and has a temperature between 4,000 and 5,000 ° C. It is possible that the inner core is the result of the crystallization of what was a liquid mass of greater magnitude and that this growth process continues.
The heat energy of the core influences the mantle, particularly in convection currents. It is currently considered that the internal core has a rotational movement and it is possible that it is growing at the expense of the external, which is reduced.
Many scientists believe that 4,000 million years ago the Earth already had a magnetic field caused by a metal core. Its formation marked the boundary between the consolidation process and the surface cooling.
The point of friction between the core and the mantle is called Gutenberg discontinuity in honor of Beno Gutenberg, a German seismologist who discovered it in 1914. It is about 2900 km deep. This limit is responsible for terrestrial magnetism, which occurs when the metallic materials of the outer core rub against the silicates of the earth's mantle.
|◄ Previous||Next ►|
|Earth's crust||Magnetism and electricity on Earth|