The earth is known to be round.Moreover, our planet is distinguished by a spherical structure and consists of a number of geospheres. That it such, we will tell in our article. In addition, you will learn how the Earth’s largest geosphere is called and what it consists of.
What is the geosphere?
The term comes from two Greek words:"Geo" ("earth") and "sphere" ("ball"). The geosphere of the Earth is a concentric shell that can be continuous or intermittent. Geospheres can intersect with each other both in space and in time. All of them are very closely related, despite the seeming autonomy of each of them.
In science, it is customary to distinguish two types of geospheres:internal, of which, in fact, consists of the "body" of our planet, and external. The first group includes: the Earth's core, the mantle (the largest geosphere of the Earth in terms of volume) and the Earth's crust. The second group is often ranked:
- lithosphere;
- hydrosphere;
- the atmosphere;
- and the biosphere.
Sometimes scientists also distinguish the cryosphere (the ice shell of the Earth), the pedosphere (soil shell), the magnetosphere (the magnetic field of the planet), the noosphere (the zone of interaction between nature and society) and others.
Создателем геосферной концепции считают Austrian geologist Edward Süss. In the future, the theory of these shells was actively developed by V. I. Vernadsky. It was he who first established that all geospheres are in constant and active interaction.
The largest geosphere of the Earth
Next, we dwell in more detail on one of the inner shells of our planet. It will be about the mantle - the largest geosphere of the Earth in terms of volume and mass (about 80% of the globe).
The mantle is a massive shell of 2900kilometers, located between the core and the crust. That it is the bulk of our planet. The boundary between the mantle and the crust is the so-called Moho line - a zone where a sharp increase in seismic velocity is observed. This line runs at a depth of 7 km (under the oceans) to 70 km (under the geosynclinal areas).
Of course, no one has yet hadopportunities to see the earth's mantle with my own eyes. Scientists obtain all the information about this shell either by analyzing data on the speed of seismic waves, or by studying the so-called mantle melts - rocks formed in the depth of this geosphere (basalt, kimberlite, peridotite, etc.) In the photo below - a sample of basalt.
Structure and composition of the mantle
The mantle is conventionally divided into two parts - the lower and the upper. The boundary between them (the Golitsyn layer) passes at a depth of about 670 km.
All processes in the mantle havea huge impact on the surface of our planet. In particular, its relief and the formation of the largest deposits of some minerals. In turn, the mantle itself is greatly influenced by the processes occurring in the earth's core.
The mantle of the earth is mainly composed of peridotites,perovskites and eclogites. In addition, there are rocks that are not in the earth's crust. The chemical composition of the mantle is dominated by elements such as oxygen, magnesium, iron, silicon, and calcium.
