About hundreds of millions of years ago, when the Earth was formed, the Earth was a hot ball of molten substances containing everything that we see around us today. But gradually, with time, the upper surfaces began to cool and solidify. This process of cooling continued for millions of years forming the upper surface of the Earth - the Crust. The crust, thus, floats on semi-molten layers of elements and rocks of the mantle. This layer is also called Asthenosphere where the radioactive processes still continue and the heat generated here comes towards the surface of the Earth in Convection currents.
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| Convection currents within Earth |
It is believed that there were two large blocks of land formed from a single large block the
Pangea - the Laurasia plate(Sometimes called Angaraland) and the Gondwanaland. While the former was in the Northern hemisphere the Gondwanaland was in the southern hemisphere. The convection currents broke and drifted these large chunks of land according to the
Continental Drift Theory. These gave rise to formation of different tectonic plates. These tectonic plates further collides and slide against each other giving rise to major earthquakes and large sea waves. The evidence of a single large landmass is provided by the fact that the soil types and kind of fossil that are found on both the sides of the Atlantic Ocean.
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| Pangea |
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| Different tectonic plates |
In this way, the modern world map came into existence, along with the 7 major tectonic plates - the North American, the South American, the Eurasian, the African, the Indo-Australian, the Pacific and the Antarctic plates.
