Sometime Earth had a completely different look than now: the continents of today, with their contours of which we are so familiar, did not exist. The entire land made up one huge meal: a supercontinent. Then it broke into pieces under the action colossal tectonic movements from the depths of the planet, and the pieces, moving away from each other, made up, finally, the current configuration, which recognize anytime on maps and globes. But what’s more interesting is yet to come: some scientists say that this did not happen just once, but several times, especially going to happen. A few hundred million years, continental geography of the planet will be completely different than today and would come again supercontinents time …
So fragmentation supercontinents followed the movement and collision of continents, would constitute a sequence of unique and unrepeatable events, only one of the scenarios of this kind that keeps succeeding face of the Earth.
There are, say these experts, a cycle of supercontinents : snap, followed by ballet fantastic drift cotinentelor stretched for hundreds of millions of years, then reassembling masses of land in other configurations, then moving further these rafts earth on the sea of magma underneath, toward each other, their union gradually, in stages, to form, ultimately, a new supercontinent. And he will live because a living, then it will fragment and so on, forever … or at least as long as it will take Terra.
Past research suggests the planet that she already lived through several such cycles.
As a result, scientists have described several such supercontinent; the existence of some of them – the oldest – is questionable, but others more recent, is supported by arguments that seem sufficiently strong to allow us to believe that these alternating breaks and reunions of large masses of land is indeed a characteristic of the Earth – one of the many extraordinary aspects of “life” of this planet.
The data that support these theories are geological data, paleomagnetic and others; more efficient technologies for measuring various features of Earth’s planetary mean that these theories evolve and become increasingly more accurate.
However, as often happens in science – especially when it comes to events very old, whose existence must be inferred by interpreting a large number of data – scientists disagree on the past of the planet, in terms supercontinents that They were on it.
The vast majority of the scientific community agrees that the last supercontinent, Pangaea, formed 300 million years ago; by fragmenting it formed his first two land masses (Laurasia in the northern hemisphere and Gondwana in the south) and through their fragmentation, followed by fragments displacement and realipirea some of them in other ways resulted current configuration.
But when it comes to what it was before Pangaea, opinions differ.
One of vision brings to the stage the image of a planet that had succeeded so far at least 5 supercontinent:
- Ur (Vaalbara), the oldest – from 3.6 to 2.8 billion years ago
- Kenorland – in 2.7 to 2.1 billion years ago
- Columbia (Nuna) – 1.8-1.5 billion years ago
- Rodinia – in the 1.25 to 0.75 billion years ago
- Pannotia – 600 million years ago
- Pangaea – 300 million years ago
It shows here that in this conception, is considered a characteristic cycle supercontinents “innate” Earth, which began to manifest as soon as the planet cooled and was structured enough to be able to talk about land and ocean.
In contrast to this view, another model, called Protopangea-Paleopangea says that, in fact, the cycle began only supercontinents ago 600 million years; that from now until 2.7 billion years ago to 600 million years, there was only one supercontinent.
- The continents are defined (rather vague) as large expanses of land, separated by stretches of sea. They are components of tectonic plates, pieces of hardened crust that float on magma (viscous material, formed by molten rock) from Earth’s mantle. The composition tile floors fall and marine seabed and ocean. The main tectonic plates are number 7 or 8 (depending on how they are defined), whom add their are a number of smaller plates.
- The formation of the continents and supercontinents is related to phenomena such as tectonic plates(their movements and geological phenomena that occur at their edges, where the plates are in contact with each other) and volcanism , and evolution of these large masses of land is correlated with changes of the planet’s
- In periods when there is a single supercontinent, when all the land (or almost everything) is practically merged in one stretch, there is obviously a unique body of water: a super ocean. Their scientists and gave them names; thus, the supercontinent Rodinia, the model no. 1 (the many successive supercontinent), was surrounded by a super ocean called specialists Mirovici, while super-ocean surrounding the most recent supercontinent, Pangaea, was given the name of Panthalassa .