Formation of Continents

In Context

• According to a recent study published in Nature journal, giant meteorite impacts could be responsible for the formation of continents on Earth.

More about the study

• About:
  • According to the study, Earth’s continents were formed by massive meteorite impacts that were prevalent during the first billion years of our planet’s four and a half billion-year history.
  • Meteorite impacts generated massive energy to form oceanic plates, which later evolved into continents.
• The process:
  • The giant meteorite hit Earth and melted the outer shell of the Earth or the lithosphere, according to the study.
  • This impact released the pressure on the underlying mantle. 
  • As a result, the mantle likely melted, creating an oceanic plateau.
• Significance:
  • Earth is the only planet that is known to have continents. 
  • What amazes scientists is the evolution and formation of the continents, making it the most researched field amongst planetary scientists. 
  • First of its kind:
    • It is well known that numerous such impacts have hit the planet from archaic times.
    • This research provides the first solid evidence that the processes that ultimately formed the continents began with giant meteorite impacts, similar to those responsible for the extinction of the dinosaurs, but which occurred billions of years earlier.
  • Key to reserves of metals: 
    • Understanding the formation and evolution of continents is important as it is the key to reserves of metals such as lithium, tin and nickel, which are required to develop batteries, the study noted.
      • Shallow melting of the rocks separates the lower density elements, such as lithium, from the higher density ones, such as iron.
      • Eventually, the lower density elements rise to the surface as a granitic continental crust. 
• Meteorites impact other planets too, so why is such a phenomenon exclusive to Earth?
  • Other rocky planets and the moon had little or no water by the time the flux of effects declined.

Alternative theories of Continent formation

• The most commonly accepted theory in place attributes continent formation to the movement of tectonic plates.
• Earth is uncommon among the planets and also from our moon that its outer surface is divided into rigid slabs, which were called tectonic plates by Wegener in his theory. 
  • While their surfaces exhibit evidence of recent deformation, neither planet has a surface divided into plates.
• As the technology advanced, making it possible for deeper exploration, the theories of continental drift and seafloor spreading got positive scientific data in support.
  • The two theories were merged to develop the modern plate tectonic theory.

Source: DTE