What is the plate tectonics theory and why is it useful for us? The Plate Tectonics theory, a theory of the geological sciences, explains a wide variety of natural phenomena occurring on planet Earth.
In very broad terms, the plate tectonics theory is based on the idea that the lithosphere is broken into what we call plate tectonics, i.e., the pieces that make up the plate.
Continuing in this vein, if you want to learn more about tectonic plates, we suggest you read this informative article in which you will find all the explanations you need as well as what types of tectonic plates exist, why they move, and much more.
What is the plate tectonics theory and what are tectonic plates?
Simply explained, tectonic plates are components of the lithosphere, or the Earth’s solid surface layer, and can be up to 100 km thick. Tectonic plates are suspended in a viscous layer known as the asthenosphere, which allows for lateral movement or displacement of the plates.
The plates are deemed stiff because they contact one another laterally without deformation, except at their edges, which are significantly modified.
In addition, there are fourteen major tectonic plates and forty-six smaller tectonic plates that make up the lithosphere. The size of the main plates is what differentiates them from the sizes of the minor plates, with the major plates being the larger of the two.
The plate tectonics theory is based on the idea that the lithosphere is broken into what we call plate tectonics.
The following is a list of the 14 primary plates:
- North American plate
- South American plate
- Pacific Plate
- African plate
- Eurasian plate
- Australian plate
- Antarctic plate
- Caribbean plate
- Cocos Plate
- Plate Nazca
- Plate of the Philippines
- Arabic plate
- Scotia plate
- Plate Juan de Fuca
Types of tectonic plates
Depending on the type of Earth’s crust that forms them, tectonic plates can be:
- Oceanic plates: They are made up of oceanic crust, which is thin and basic in nature, with a larger amount of iron and magnesium. In general, it is completely buried in ocean water..
- Mixed plates: made up mostly of continental crust and, to a lesser extent, oceanic crust. Some people refer to them as continental plates since their composition is dominated by continental crust. This is the case for the majority of tectonic plates.
In turn, tectonic plates can be classified according to the type of boundary or edge they present:
- Divergent boundary: tectonic plates migrate away from one another as a result of processes that force them apart. This sort of boundary can be found on both the oceanic and continental plates. As the plates move apart, magma rises and seeps through the faults, causing a new crust to emerge.
- Convergent boundary: when two tectonic plates clash head-on, one plate descends beneath the other. Subduction is the process of sinking. The subducting plate is usually the densest, and once in the mantle, it partially melts and creates magma. When two plates with the same density collide, such as when two continental plates collide, the process of shelling occurs. Neither plate collapses during this process, but the edges of the two plates are bent vertically and linked by a seam zone.
- Sliding boundary: tectonic plates slide in parallel but in different directions. As in the prior examples, there is no crustal formation or crustal breakdown. These limits are distinguished by intense friction between the plates.
Why do tectonic plates move?
It is still not entirely clear why the tectonic plates move in the way that they do.
The plate tectonics theory first appeared between the years 1960 and 1970 and is still in the process of being developed. This much is known. It has been demonstrated beyond a reasonable doubt that a number of variables contribute to plate sliding.
Temperature, or more specifically, the geothermal gradient, is one of the most important elements in plate motion because it generates circumstances that are favorable to motion. These characteristics include a lithosphere with a high viscosity that is able to flow across an asthenosphere with a lower viscosity.
Additionally, the geothermal gradient across the globe is fully heterogeneous, and as a result, the crust is made up of elements that range in density. The various motions of the tectonic plates are caused by gravitational forces, which are made possible by the fact that the crust is composed of a variety of different materials with varying densities.
Consequences of the movement of tectonic plates
Plate motions have many impacts, the majority of which are felt towards the margins of the plate and in the regions that are close to those edges.
The plate tectonics theory explains many of them, and we also have them in the list:
- Fault valleys: These are geological faults formed by the separation of two plates having divergent limits.
- Volcanoes can be formed by magma that rises during plate separation caused by divergent boundaries, as well as by plate subduction induced by convergent boundaries. You may learn more about volcanism, which is caused by tectonic movement, by reading the article “How volcanoes develop.”
- Earthquakes are induced by the collision of plates with converging borders, as well as friction between plates with sliding boundaries. If you want to understand more about earthquakes, read the difference between earthquakes, tremors, and earthquakes; what it is, how it occurs, and its types.
- Plates clash with one another, causing folds and deformations at their edges, during the process of plate retreat with converging borders. Mountains and mountain ranges are generated as a result of folds and deformations.
- Transformational fractures can be seen as geological discontinuities in the ground or as highly tectonized rocky regions. Friction between plates with sliding borders causes faults.