Geological and Biological Changes

Cryptozoic Eon

It opens with the very beginning of the earth, when it starts as a whirling mass of gas, held by the gravitational pull of the sun. The gases condense into liquids and liquids solidify to form the outer crust of the earth. The thick steamy vapour surrounding the earth falls down as heavy rains to produce the first oceans and rivers.

The rocky crust, backed by hot winds and cooled by heavy rains, weathers down to form soil and sand.

Pre-Cambrian Era 

  • 4600 million to 600 million years ago

First signs of life represented by microcosms, appear in the Pre-Cambrian Era.

Phanerozoic Eon

  • 600 million years to Holocene Age (Recent)

It comprises the Palaeozoic, Mesozoic, Caenozoic and Quaternary eras.

Palaezoic Era

  1. Cambrian: 600 to 500 million years ago
  2. Ordovician: 500 to 440 million years ago
  3. Silurian: 440 to 400 million years ago
  4. Devonian: 400 to 350 million years ago
  5. Carboniferous: 350 to 270 million years ago
  6. Permian: 270 to 225 million years ago

Mesozoic Era

  1. Triassic: 225 to 180 million years ago
  2. Jurassic: 180 million to 135 million years ago
  3. Cretaceous: 135 million to 70 million years ago

Caenozoic Era

  1. Palaeocene: 70 million to 60 million years ago
  2. Eocene: 60 million to 40 million years ago
  3. Oligocene: 40 million to 25 million years ago
  4. Miocene: 25 million to 3 million years ago
  5. Pliocene: 3 million to 1 million years ago

Quaternary Era

  1. Pleistocene:  1 million to 10 thousand years ago
  2. Holocene: from 10,000 years ago