Eras

• Cenozoic

  • 66mya-present
  • Ice sheets cover much of North America
  • Continents take on their present shape
  • Formation of the Rocky Mountains completed
  • Modern forms of life evolve
  • Age of mammals
  • Human beings develop
• Mesozoic

  • 245mya-66mya
  • The formation of the Rocky Mountains begins
  • Innuitian Mountains formed
  • Shallow seas in the interior of North America at various times
  • First birds and mammals
  • First flowering plants
  • Age of reptiles, such as dinosaurs
• Paleozoic

  • 570mya-245mya
  • Periods when large parts of North America are covered by shallow seas
  • The Appalachians formed
  • First plants and animals appear on land
  • Large swamps - coal formed from this vegetation
  • First insects
  • Age of amphibians and fish
• Precambrian

  • 4600mya-570mya
  • Precambrian shields, such as the Canadian Shield, Brazilian Shield, and Australian Shield are formed
  • First single-celled organisms
  • First multi-celled organisms