When Were Tectonic Plates Formed ?
Plate Tectonics began somewhere between 3 and 3.5 billion years ago and as a result the earth became full of volcanoes, mountains, valleys, oceans and continents. But when did all this begin?
Massive asteroids and meteorites bombarding the earth from space, should have helped the creation of tectonic plates, and the formation of earth’s magnetic field. The earth was born from the embers of our solar system. About 4.5 billion years ago, the young earth had a shell called the crust. Between 4.1 and 3.5 billion years ago, earth was hit by remnants from other planets and comets, thereby causing the earth’s crust to sink into deeper mantle at ocean trenches — a process called subduction — and the plate tectonics was kickstarted. Because of the massive impact, the molten material inside earth would have been pushed around, accentuating the temperature difference between outer and inner earth, resulting in the amplification of convection currents, thereby creating our earth’s magnetic field.
The process called subduction, leads to the destruction of tectonic plates, the formation of mountains, continents, volcanoes, and earthquakes. Tectonic plates cannot drift around, unless they are destroyed by a process of subduction. So that leads to our conclusion that subduction caused the creation as well as destruction of tectonic plates. Indeed, impact cratering was also responsible for creation of magnetosphere. Presence of felsic rocks, which form only when you have heat and water, near the subduction zones, proves that tectonic plates were forced under each other.
Presence of felsic rocks, like granite, on the earth’s crust, about 3.5 billion years ago is a testimony to this. Because felsic rocks are preserved in shales. And shales have different mixtures of titanium isotopes, by which their age could be determined. Tectonic plates development would have occurred over hundreds of millions of years, somewhere between 4.1 billion years and 3.5 billion years. Since a molten earth could by itself not have given rise to tectonic plates, it required some sort of celestial force to jump start it, the above theory is convincing.