If you have ever wondered if the continents can move, we are going to clear that doubt once and for all and we will tell you that yes, in fact they do and in this article we will explain whatwhat is continental drift?, what are tectonic movements?, the scientist who proposed the theory of all this and much more, so we invite you to continue this reading.
Continental Drift Theory
La continental drift has been defined as the constant and very slow movement of the different masses that form the continental spaces of our planet in relation to the others, so it can happen that they move away or come closer, which has happened in a period that includes millions of years.
The cause of the movement that gives rise to the continental drift is that the layer that is under the lithosphere of the earth, which is its core, is liquid and is in constant movement. On top of that layer the different tectonic plates swim, with thrusting or separating movements, moving in a correlated way, as if they were tapestries on a floor treated with wax.
alfred wegener
In 1912, the German geophysicist Alfred Wegener (1880-1930) proposed his theory on the continental drift as an explanation for the fact that it had been scientifically proven that the situation in which the continents are at this time is different from what the geological evidence obtained thanks to the fossil records suggests.
At first, this theory about the movement of the continents was not enthusiastically received by the most outstanding geologists of that time, being relegated almost to oblivion, until in the 60s, when it was possible to understand the existence and functioning of the tectonic plates and it was possible to express in a more appropriate way the movement of the continents.
other scientists
On the other hand, the thought that the profiles of the continents fit together, as if they were part of a puzzle, is nothing new. It had already been proposed in the XNUMXth century by the German naturalist Alexander von Humboldt, who had established a theory about it.
It took some 50 years for the French scientist Antonio Snider-Pellegrini to conclude from his observations that the existence of the same evidence of fossils in the coastal areas of continents as far apart as Africa and America I could only have one explanation and that was that at some geological moment on Earth they had been united, either physically or through land bridges that were now submerged.
But the first complete theory that gave an explanation for this prodigy came with Wegener, who also coined the term Pangea, as the name that should be given to the supercontinent that made up all the current continents when they were together. Pangea is a word made up of two Greek words, pan, which means everything, and gea, which means earth.
Evidence of Continental Drift
Researchers have concluded that there are many indications of the reality of the existence of the continental drift, among which are the following:
The fact is that when observing a world map, it can be concluded that the orography of the coasts of several continents coincide with each other, also if we could compare the limits of the continental shelves, we would observe that the edges complement each other.
There are geological indications that the continents were once very close, because multiple rock formations or mountain systems have the same age and the same kind of stones that went through the same kind of metamorphic process, on continents that today are far apart and in different places.
The finding of fossils of animals and plants in the coastal orography of the continents that are far apart today is fully explained if the continents in previous ages could have been closer.
Paleoclimatic studies that use the rocks found in the subsoil of the earth's crust to establish the Temperature and Humidity of antiquity in several places on the surface, they have no explanation with the current position in which the continents are found. On the other hand, if you take into account the hypothesis that there was only one continent at some point.
Continental Drift Stages
It is theorized that Pangea was neither the only nor the first supercontinent. It has been argued that others could have existed before, that they were broken into pieces, from which other supercontinents could be formed and so on repeatedly until what we find today. This process of unification and fractures can be roughly synthesized in the stages described below:
Rodinia
Rodinia was a supercontinent born approximately 1100 million years ago, it was formed by reason of a displacement or drift of the existing continents that were coming together. Scientists do not rule out the possibility that other previous continents may have existed, but they have not been able to obtain sufficient evidence of their existence.
Then, around 750 million years ago, Rodinia began to break apart and a new supercontinent was born from its pieces.
Pannotia
Then, about 600 million years ago, the formation of a second supercontinent took place, which was named Pannotia, and which only survived for about 60 million years.
Gondwana and Proto-Laurasia
About 540 million years ago, Pannotia fractured into two smaller supercontinents called Gondwana, located in the southern hemisphere, made up of what is now known as Africa, South America, India, Oceania, Madagascar and Antarctica. Proto-Laurasia, which was in the northern hemisphere, made up of Asia, Europe, and North America. In the space that separated them, a new ocean called Proto-Tethys was established.
Laurentia, Siberia and Baltica
They are three smaller supercontinents that were formed about 500 million years ago, as a result of the fracture of Proto-Laurasia, which in turn gave way to the existence of two new oceans, called Iapetus and Khanty.
avalonia
Around 485 million years ago, during the Ordovician period, a microcontinent split from Gondwana and was baptized Avalonia, made up of what is now known as the United States, Nova Scotia and England, beginning to transit towards the northern hemisphere, until hang out with Laurentia. In this way, Baltica, Laurentia and Avalonia came together to form Euramerica.
Approximately 440 million years ago, Gondwana began a very leisurely journey from the ascending hemisphere, which put it on a collision course with Eurasia, losing two microcontinents in the process that went on to form what is now North China and South China. who went their own way.
Like them, other pieces broke apart and proceeded to join again, but in other locations, during the process the oceans were closing and the continents were getting closer again.
Siberia and Pangea
About 300 million years ago, at the time of the Permian period, only two immense great continents had already been formed, which were called Siberia and Pangea, they were very close and were surrounded by a single ocean called Panthalassa.
Pangea
About 251 million years ago, during the Triassic period, a great retreat of the Seas and oceans and the terrestrial surface increased considerably, as a result of the land that arose from the bottom of the ocean. Thanks to continental drift, the unification of the continents took place and Pangea emerged, the monumental supercontinent that was shaped like a C, engulfing the Tethys Sea inside it.
Continental Drift and Plate Tectonics
La continental drift arises from the displacement of the plates on the Earth's mantle. To this day, Wegener's theory is the antecedent of what is known as plate tectonics, a concept in which it is included. The emergence of the theory of plate tectonics was the product of a collective study that took place in 1960, by the following scientists:
"Robert Dietz, Bruce C. Heezen, Marie Tharp, Harry Hess, Maurice Ewing, and Tuzo Wilson."
This theory of plate tectonics manages to explain the displacement of the continents in the place where they converge in the mantle of the planet Earth, whose movements are due to the constant reconfiguration in the upper and rigid stratum, which is the lithosphere.
In this way, both the continental drift such as the expansion of the ocean floor are the product of a process that has lasted for billions of years, which makes the tectonic plates move and collide with each other and the effects of this movement are the deformations of the surface that today form what is known as the terrestrial relief.