The last supercontinent, of which there were several in Earth's past, was called Pangea. It disintegrated into Laurasia and Gondwana, which later gave rise to all modern continents of our planet, about 200 million years ago. Geologists say that in the near (by geological standards, of course) future one common continent will again form on the planet. The new results of scientists even make it possible to clarify where, in general terms, this formation will occur.
A bit of history
In 1915, the German scientist Alfred Wegener published a book entitled “The Origin of Continents and Oceans” (Die Entstehung der Kontinente und Ozeane), in which he outlined the theory of continental drift, that is, the movement of continents. I must say that the idea of the mobility of the earth's crust at that time was not new, but Wegener was the first to turn it into a scientific hypothesis, supported by a number of factual observations.
Among other things, in his book, Wegener suggested that at one time, in the distant past, there was a kind of supercontinent, which he christened the Urkontinent, which later split for unknown reasons. Thirteen years later, the works of the symposium of American geologists were published, who, during one of the discussions, came up with another name - Pangea, which is translated from Greek as "all-earth". This name for the supercontinent, unlike that given by Wegener, stuck.
Pangea
At the time of the creation of the theory of continental drift, it had many opponents. Among other things, this was due to the fact that Wegener was ahead of his time - the explanation of the movement of the continents was given only in the 30-40s. Geologists associated it with convection processes inside the mantle. The final confirmation of the theory of tectonic plates and continental drift was obtained only in the 60s of the last century, and then the controversial hypothesis became the generally accepted theory.
Over time, scientists have come to understand that the processes of formation and destruction of supercontinents are of a periodic nature and have occurred more than once throughout Earth's history. Researchers are now using a bunch of techniques to determine the movement of continents in the past. In addition to the banal comparison of geological deposits, for example, they find the same (or just very similar) species of living things in regions that are now separated by thousands of kilometers of water. Or they measure the residual magnetization in rocks, which has been preserved from the moment of their solidification.
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At the moment, all these methods, strengthened by computer models, allow with a sufficient degree of confidence to reconstruct the geological history of the planet for only the last 500 million years (for comparison, the age of the Earth is 4.6 billion years), but scientists are trying to look much further into the past. The reader should keep in mind that many of the discoveries that will be discussed below are relatively fresh and, strictly speaking, still carry the status of hypotheses.
So, there were six supercontinents in the history of the planet:
Vaalbara - existed 3.1-2.8 billion years ago
Kenorland - existed 2.7-2.5 billion years ago
Nuna (Colombia) - existed 1.8-1.5 billion years ago
Rodinia (from Russian "to give birth") - existed 1.1-0.75 billion years ago
Pannotia - existed 600-540 million years ago
Pangea - existed 300-200 million years ago
To the future
By knowing how continents have behaved in the past, geologists try to predict how they will behave in the future. To do this, they use computer models calibrated from the results of practical research - for example, the already mentioned paleomagnetic ones. It is clear that, even despite the calibration, the predictions of the models differ.
Novopangea. Image from NASA website
At the moment, there are three main scenarios for the development of events, each of which will lead to the formation of a supercontinent. The continents obtained as a result of these options were named Novopangea, Amasia and Pangea Proxima.
The first supercontinent, Pangea Proxima, will emerge as North America moves eastward. It will pull the South Pole along with it, the Atlantic Ocean will disappear, and the resulting supercontinent will stretch from the North Pole to the South Pole across the equator. The second option was named Amazia. This supercontinent is formed as a result of the confluence of Asia and North America, and all land will be concentrated at the North Pole. Finally, the third option - Novopangea - will arise after the disappearance of the Pacific Ocean and the closure of North America with Africa and Eurasia (Antarctica and Australia will already catch up with them).
In a new work published in Nature, Yale scientists were trying to figure out exactly where the new supercontinent would be located. As part of the work, they considered the option with Amazia. To determine the location of the future continent, they built a mathematical model of the mantle, taking into account the irregular shape of the Earth. The location of the continent was determined by the location of the point of minimum moment of inertia of the continent (such points they called the center of the continent).
Scientists have found that the angles between the radii connecting the centers of the supercontinent to the center of the planet for Nuna and Rodinia were 88 degrees, and for Rodinia and Pangea - 87 degrees, respectively. The scientists' model showed that the next supercontinent will be formed in such a way that the angle between the radius vector of its center and Pangea will be approximately 90 degrees.
The researchers emphasize that their result is quite unexpected - until recently, geologists assumed that a new continent would form on the site of Pangea or on the opposite side of the planet from its location. Perhaps, it was precisely because of its unexpectedness that the work caused an ambiguous reaction from specialists. Thus, some have stated that the article is “excellent” and “impressive”, while others believe that it is nothing more than a hypothesis with its flaws.
Meanwhile, it is not yet a fact that a new continent is actually being formed - in September an article was published in Terra Nova, the authors of which argue that South America and Antarctica will not be able to join the new continent. The reason for this is “hot spots” in the mantle - regions where temperatures are above average. Geologists have determined that two zones - one at a depth of about 2,800 kilometers under Africa and the other under the South Pacific - will prevent the continents from uniting. This is due, among other things, to the uplift of the crust in these regions by 1-2 kilometers. In general, time will judge who is right and who is wrong here - some 500 million years remain until the formation of a new continent.