This first eon in which the Earth existed is what is known as the Hadean period, named after the Greek word “Hades” (underworld) which refers to the condition of the planet at the time. During this time, the Earth’s surface was under a continuous bombardment by meteorites, and volcanism is believed to be severe due to the large heat flow and geothermal gradient. Outgassing and volcanic activity produced the primordial atmosphere. Condensing water vapor, augmented by ice delivered by comets, accumulated in the atmosphere and cooled the molten exterior of the planet to form a solid crust and produced the oceans. This period ended roughly 3.8 years ago with the onset of the Archean age, by which time, the Earth had cooled significantly and primordial life began to evolve.
As the surface continually reshaped itself over hundreds of millions of years, continents formed and broke up. The continents migrated across the surface, occasionally combining to form a supercontinent. Roughly 750 million years ago, the earliest-known supercontinent of Rodinia began to break apart, then recombined 600 – 540 million years ago to form Pannotia, then finally Pangaea, which broke apart 180 million years ago, eventually settling on the configuration that we know today.
We have written many articles about the Earth for Universe Today. Here’s an article about the temperature of Earth, and here are some facts about the planet Earth.
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