THE GEOLOGIC TIME SCALE

• Pre-Cambrian


  more than 85% of the Earth's history fall under this supereon, from 4.6 billion yrs ago to 540 million yrs ago
• Hadean Eon 


  The solidification of the earth's continental and oceanic crust 4.6 billion years ago
• Archean Eon


  The evolution of earth's first life forms 4 billion years ago
• Proterozoic Eon


  The appearance of multi-celled animals, and the gathering of land masses to form continents