Following what we saw earlier in Alfred Wegener 's articles and the theory of Continental Drift , science advanced until, in 1968, the current theory of plate tectonics was accepted. This theory states that for billions of years, the plates that make up the continental crust have been undergoing a slow but continuous movement. If you want to learn more about plate tectonics, I recommend you keep reading this post
Background
Before plate tectonics was accepted by the scientific community, the scientist Alfred Wegener proposed the theory of continental drift. It was based on the drifting movement of the continents. He compiled a large amount of information that explained many of the doubts surrounding the shape of the continents and the distribution of animal and plant species.
Paleoclimatic evidence was gathered that indicated the type of climate that existed in the supercontinent known as Pangea. Fossils of animals that existed both on one continent and another were also found and it is because before those lands formed a single surface.
Earth's magnetism was also highly relevant due to the orientation of rocks and minerals. This theory was accepted years after Wegener's death. However, it didn't explain why the continents moved. In other words, what was the reason why the continents could shift across the entire continental crust? Plate tectonics provides the answer.
The movement is due to the continual formation of new material from the mantle. This material is created in the oceanic crust. In this way, the new material exerts a force on the existing one and causes the continents to shift.
Plate dynamics
As we have mentioned, this theory complements and fully explains continental drift. And it is that it was only necessary to know which was the engine that made the continental plates move.
Continents collide or break apart, oceans open, mountains rise, and the climate changes , all of which significantly influence the evolution and development of living beings. New crust is constantly being created on the ocean floor. This crust grows very slowly, only one or two kilometers per year. However, this continuous growth causes the crust to be destroyed in areas of oceanic trenches and leads to collisions between continents.
All these actions modify the Earth's surface. Thanks to these collisions and plate movements, numerous seas and oceans and enormous mountain ranges like the Himalayas have been created . Furthermore, the study of plate tectonics allows us to better understand seismic activity and its impact on our planet.
Basis of the theory
According to the theory of plate tectonics, the Earth's crust is composed of numerous plates that are constantly moving. These plates rest on a layer of hot, flexible rock. Looking back at the Earth's layers, we can see that in the upper mantle there are convection currents caused by changes in the density of materials.
Seeing that the densities of the materials are different, the rocks begin to shift from the densest to the least dense. As with atmospheric dynamics, when an air mass is denser, it will move to that area where it is less dense. The movement is always the same.
Well, the continuous movement of these convection currents of the mantle are those that, as the layer of materials on which the plates rest is flexible, which make them continuously displace.
Geologists have not yet determined exactly how these two layers interact , but the most advanced theories state that the movement of the thick, molten material of the asthenosphere forces the overlying plates to move, subduct, or rise. This interaction is key to understanding phenomena such as earthquakes and the formation of volcanoes.
To be better understood, the heat tends to rise. In planetary dynamics, heat is less dense than cold, therefore it always tends to rise and be replaced by denser material. Therefore, between the sum of the convection currents of the mantle and the pressure exerted by the birth of new oceanic crust, the plates are in continuous movement.
The same principle applies to hot rocks beneath the Earth's surface: molten material from the mantle rises upwards , while cooler, hardened material sinks further down.
Types of tectonic plate movement
The movement of tectonic plates is extremely slow, as we mentioned earlier. It only moves at a speed of about 2,5 km per year. This speed is roughly equivalent to the rate at which fingernails grow.
The movement of all the plates does not occur in the same direction, which is why they frequently collide with each other, resulting in earthquakes on the surface. If these collisions occur at sea, tsunamis occur. This is due to the collision of two oceanic plates.
All of these phenomena occur with greater intensity at plate boundaries. This movement is often unpredictable, so the presence of earthquakes cannot be predicted in advance. Therefore, it is important to know the places at greatest risk of earthquakes, both for prevention and for education about this natural phenomenon.
The types of movements that exist are:
- Divergent Movement: It is when two plates separate and produce what is called a fault (hole in the earth) or an underwater mountain range.
- Convergent Movement: It is when two plates come together, the thinner plate sinks over the thicker one. This produces the mountain ranges.
- Sliding movement or Transformants: The two plates slide or slide in opposite directions. They also cause failures.
Once all this is known, scientists can estimate the occurrence of certain earthquakes or predict the movement of continents over thousands of years. The current movement of the continents is one of drifting apart. However, the Strait of Gibraltar will be completely closed in 150 million years , and the Mediterranean Sea will disappear. In fact, research on earthquakes in different regions, such as Nepal, can offer valuable information about these ongoing movements.
I hope you liked the theory of plate tectonics and learned something more about our planet.
