Lithosphere (Meaning and Explanation)

We explain what the lithosphere is, its layers and its importance. In addition, the continental lithosphere and the oceanic lithosphere.

What is the lithosphere?

The lithosphere or lithosphere is the most solid and superficial layer of planet Earth that is, the most rigid and external of all. It is formed by the Earth's crust and the upper layer of the Earth's mantle and is the coldest surface on the planet, on which all living beings live.

The term lithosphere comes from the Greek words lithos (“stone”) and sphaira (“sphere”). This layer is part of the geosphere (which is the solid part of the planet) and varies in thickness. It is not easy to determine exactly where the lithosphere begins and ends, although the atmosphere and asthenosphere (upper mantle zone) are often used as boundaries.

There are two types of lithosphere:

continental lithosphere. It is made up of the continental crust (that is, the continents) and the outermost region of the Earth's mantle. It is mostly made up of granitic type stones and reaches around 120 km thick.
oceanic lithosphere. It is the portion of the Earth's crust that makes up the ocean floor. It is a much thinner layer than the continental layer (barely 65 km thick) and is made up, mostly, of basaltic rocks.

The lithosphere It is fragmented into different blocks known as tectonic plates (or lithospheric plates) on which the Earth's crust is located. These plates move a few centimeters a year. The movement of the plates occurs due to convection currents and can cause friction or separation between plates, which generates processes such as orogenesis (formation of mountains and geographical features) and magmatism or volcanism.

Characteristics of the lithosphere

Some characteristics of the lithosphere are:

Location. The lithosphere is one of the layers of the Earth and is made up of the Earth's surface and the outer layer of the Earth's mantle. These two are the outermost layers of the planet.
Size. The lithosphere has a variable extent, usually 100 or 150 km deep.
Temperature. The lithosphere has temperatures that vary depending on different locations and depths on Earth: on the Earth's surface, for example, the temperature is similar to that of the environment. The temperature of the lithosphere increases as you descend and in the external zone of the mantle it can exceed 1000 °C.
Function. The lithosphere is a fundamental layer for the development of life on planet Earth because it includes the Earth's surface, which is the layer that houses living organisms. It is thanks to the physical and chemical conditions provided by this layer that plants, animals and humans can develop on Earth.
Structure. The lithosphere is a solid and rigid layer formed by different types of materials, such as silicates or metals. It is made up of tectonic plates that are large fragments of solid rock that are in continuous movement.

Layers of the lithosphere

The lithosphere is made up of two main layers:

the earth's crust. It is the outermost solid region of the globe, where living beings live. It can be of two types: continental crust, when it is part of the continents, and oceanic crust, when it is part of the seabed.
The upper region of the Earth's mantle. It is the outer zone of the inner layer of the planet called the Earth's mantle. The Earth's mantle is the most abundant layer on the planet (occupying 84% of the Earth) and is composed of the upper mantle and the inner mantle. The mantle is made up of silicates (materials made up of oxygen and silicon) and extends from the end of the Earth's crust to the outer part of the planet's core (about 2900 km deep). The upper mantle is a very dense and viscous layer, over which the tectonic layers move.

tectonic plates

The plate tectonics It is the theory that maintains that the lithosphere is made up of tectonic plates, which are fragments of rock that slide over the asthenosphere. These plates are in continuous movement and can get closer or apart from each other which causes phenomena such as the formation of mountains, the formation of volcanoes, seismic phenomena, the formation of depressions, among others.

Plate movement is generated by convection currents (variations in temperature and density) and generates interaction between the edges of the plates in phenomena known as:

Divergent limits. Tectonic plates separate and magma emerges from within the Earth, causing the formation of volcanoes.
Convergent limits. Tectonic plates collide with each other and mountains are formed. The process of subduction can also occur, when one plate sinks under the other, generating the appearance of mountain chains..
Transforming limits. Tectonic plates slide laterally without destruction of the lithosphere. These movements generate earthquakes or faults.

Importance of the lithosphere

The lithosphere is a very important layer of planet Earth, because it is what contains the earth's crust on which living beings live such as animals, plants, bacteria, fungi and humans. It plays a fundamental role because it provides the environment conducive to the development of life and makes resources and nutrients available that allow the feeding and development of living organisms.

Regarding human development, the lithosphere is of great importance because it is a source of resources and natural goods that human beings use for different purposes and that are the basis of many industries. The earth's surface provides human beings with materials and resources for the development of the textile, food, automotive, oil, and metallurgical industries, among many others.

The lithosphere is the outermost layer of the planet Earth and it is there where movements and phenomena that modify the life of organisms take place, such as seismic activity (tremors, earthquakes, seismic faults), magmatic activity (volcanoes) or mountain formation (orogenesis). Furthermore, it is the only terrestrial layer that humans have been able to study directly so it is the layer about which we have the most information and the one that is best known. The other layers are found at a great depth to the Earth's surface and are only known from measurements, experiments and scientific deductions.

The geosphere, the hydrosphere, the atmosphere and the biosphere

The different systems that make up planet Earth are known as “spheres.” One of them is the geosphere, of which the lithosphere is a part, which is the solid part of the planet and is made up of:

the earth's crust. It is a solid layer and is the outermost and superficial layer of the Earth. It is the layer on which all living beings live.
The mantle. It is a layer that is located between the Earth's crust and the core, so it is considered an intermediate layer made up mostly of silicates and with a temperature that varies according to its proximity to the core. This layer is formed by the upper mantle and the lower mantle (which is at a higher temperature and denser than the upper mantle).
The core. It is a solid sphere located in the center of the Earth with temperatures greater than 4000 °C and made up mainly of iron. The core is made up of the inner core (it is solid) and the outer core (it is liquid).

The lithosphere is part of the geosphere because it is a layer formed by the crust and part of the mantle.

In addition to the geosphere, the Earth is made up of:

Hydrosphere. Part of planet Earth made up of water, that is, oceans, rivers, seas, lagoons, among others.
Atmosphere. Part of planet Earth made up of gases, among which oxygen, nitrogen and carbon dioxide stand out.
Biosphere. It is the set of living beings that inhabit and interact on planet Earth.

Continue with: Stratosphere

References

“Lithosphere” in National Geographic.
“Density and temperature of lithosphere” in Sciencing.
“Plate tectonics and how little we know about them” in the New York Times.
“What are tectonic plates and what causes their movements? in National Geographic.
“Plate tectonics: Difference between crust and lithosphere” (video) at Khan Academy.