Overview - Timescale, Physical Landscapes

Named after Hades, The Greek god and ruler of the underworld. The landscapes of the Hadean eon were extremely unstable, characterized by extreme conditions.

• 4.6 - 4 bn
  
• Division of Precambrian Superon
  
• Earth's Initial Formation
  
• Likely no viable lifeforms
  

Possible causes of Earth's formation

1. Pebble accretion - small pebble-like particles whom condensed.
   
   
2. Core accretion - The solar system was a giant cloud of dust called the solar nebula. When this giant cloud began to spin, it was broken into pieces by the force of gravity. The sun became the center of the nebula, and its pieces gravitationally joined together to form the planets. The other elements of the solar system - asteroids, comets, planets far from the sun, and comets - formed from mere clouds of gas because the solar wind could not carry away the lighter elements. On the other hand, the Earth, where we live, was deprived of light elements by the solar wind, leaving only rocks and other heavier elements, which were brought together by the Earth's gravitational pull.
   
   
3. Disk instability - The theory is that the protoplanetary disk was a rotating disk composed of dust and gas that broke up into smaller fragments due to gravitational instability caused by its massive structure. These fragments were simply clouds of gas that eventually evolved into planets.
   
   
   

Landscape Development

Surface conditions unstable as constant flow of convection currents within the mantle.

• Iron elements descended into the core of Earth
  
• elements, such as silicon, rose and became incorporated into the growing crust
  
•  The early atmosphere is thought to have started as a region of hydrogen and helium emissions. It is generally thought that ammonia, methane and neon were present after the crust cooled, with water vapor, nitrogen and more hydrogen added by volcanic eruptions.
  
• Likely an interplanetary collision, with large amounts of gas and fine debris falling to the surface and enormous amounts of heat preventing the rocks from solidifying on the surface.
  

No one knows when the planet's first crust formed, but some scientists believe that the presence of a few grains of zircon about 4.4 billion years ago confirms the existence of stable continents, liquid water, and possibly a surface temperature of less than 100°C (212°F).

As a result, very few rocks and minerals remain from that period. The oldest rocks are the pseudo-amphibolite volcanic deposits of the Nuvuagituc greenstone belt in Quebec, Canada, estimated to be 4.28 billion years old.