what are 4 important events that happened during the precambrian era?
The Precambrian Period Overview The Hadean eon took place 4,500 - 4,000 million years ago. The earth was a sphere of molten lava. The Archean eon took place 4,000 - 2,500 million years ago. The earth started cooling and the outer edge of the planet solidified from molten lava to a solid crust.