geologic time scale of earth's history

• ca. 4.6 to 3.8 billion years ago


  formation of earth's crust and ocean
• ca. 3.5 billion years ago


  oldest geological evidence of life
• ca 3.0 billion years ago


  propagation of cyanobacteria
• ca 2.0 billion years ago 


  appearance of the first eukaryotes
• ca 1.2 billion years ago 


  influx or multicellular organisms
• ca 500 million years ago


  the cambrian explosion
• ca 200 thousand years ago


  arrival of modern human