Timescale

Geologic Timescale

  • Hadean Eon 4.6 BYA - 3.8 BYA

    Hadean Eon 4.6 BYA - 3.8 BYA
    -Solar System formed
    -Earth formed
    -First rocks
    -First eon in Earth's history
    -Sun formed
    -Elements form
    -4.6 billion years ago
  • Period: to

    History of the Earth

  • Archean Eon 3.8 BYA - 2.5 BYA

    Archean Eon 3.8 BYA - 2.5 BYA
    -First life
    -First bacteria
    -Oldest fossils(microscopic bacteria)
    -Continental plates formed
    -Water forms on Earth
  • Proterozoic Eon 2.5 BYA - 570 MYA

    Proterozoic Eon 2.5 BYA - 570 MYA
    -First large oxygen supply(created by cyanobacteria)
    -First fossils visible to the naked eye
    -Life grows tremendously and thrives
    -First animals evolve
    -First stable continents
    -First multi-celled organisms
    -High oxygen levels kill many organisms
  • Phanerozoic Eon 570 MYA - Present day

    Phanerozoic Eon 570 MYA - Present day
    -Major development of plants and animals
    -Multicellular life is common
    -First mammals, reptiles, birds, amphibians, fish, plants,etc.
    -Leads into present times
    -Humans first appear
  • Paleozoic Era 570 - 225 MYA

    Paleozoic Era 570 - 225 MYA
    -Multicell animal "explosion" in diversity
    -Mountain building
    -First life out of the sea
    -First plants
    -First major extinctions
    -Formation of Pangea
  • Cambrian Period 570 MYA - 500 MYA

    Cambrian Period 570 MYA - 500 MYA
    -First period in the Phanerozoic Eon
    -Major groups of animals first appear in the fossil record
    -"Cambrian explosion" happened, when animals diversified in the Cambrian
    -First predators
    -First trilobites
    -Low oxygen levels
    -World climates are mild
    -Plants had not yet evolved
  • Ordovician 500 MYA - 400 MYA

    Ordovician 500 MYA - 400 MYA
    -Most of Earth's land located in Gondwana, a supercontinent
    -Diverse marine invertebrates
    -Warm and moist weather
    -Mass extinction
    -Oldest complete vertebrate fossils
    -Major glaciation in early Ordivician
  • Silurian 400 MYA - 395 MYA

    Silurian 400 MYA - 395 MYA
    -Melting of large glacial formations
    -Rising of sea levels
    -Stabilization of Earth's climate
    -First coral reefs
    -Big step in fish evolution
    -First life on land
    -Evolution in vascular plants
    -Major orogenic events
  • Devonian 395 MYA - 345 MYA

    Devonian 395 MYA - 345 MYA
    -Some of the earliest vascular plants
    -First trees
    -First forests
    -First land-living vertebrates
    -First terrestrial arthropods
    -3 major continental masses
    -Rapid diversification of fish
    -Raising of Appalachian Mountains
    -Extensive reef building
  • Carboniferous 345 MYA - 280 MYA

    Carboniferous 345 MYA - 280 MYA
    -Rich deposits of coal and coal beds
    -First amniote egg
    -Split up into Mississipian and Pennsylvanian
    -Increase in tree ferns
    -More tropical and humid climate than today
    -First reptiles
    -Many very large insects
    -Creation of Ural mountains in Russia
    -Larger oxygen supply than today
  • Permian 280 MYA - 225 MYA

    Permian 280 MYA - 225 MYA
    -Last period of the Paleozoic Era
    -Largest mass extinction in history
    -Forests of ferns were replaced by drought-resistant plants
    -Massive areas of land and water
    -Formation of Pangea
    -Dry conditions
    -First mammal-like reptiles(therapsids)
    -First large reptiles
  • Mesozoic 225 MYA - 65 MYA

    Mesozoic 225 MYA - 65 MYA
    -Age of the dinosaurs
    -First mammals
    -First birds
    -Unusual plants
    -First angiosperms
    -Dinosaurs and mammals evolve
    -Extinction that destroyed the dinosaurs
  • Triassic 225 MYA - 190 MYA

    Triassic 225 MYA - 190 MYA
    -First dinosaurs
    -First mammals
    -Pangea exists
    -First conifers
    -Lower sea level
    -Areas of forests and arid land
  • Jurassic 190 MYA - 136 MYA

    Jurassic 190 MYA - 136 MYA
    -First giant dinosaurs
    -Many pterosaurs
    -First birds
    -Ocean full of life
    -Vicous carnivores
    -Largest dinosaurs lived in this period
    -Abundant land plants
    -Oceanic icthyosaurs lived in the seas
    -Ferns and cycads
    -Break-up of Pangea
  • Cretaceous 136 MYA - 65 MYA

    Cretaceous 136 MYA - 65 MYA
    -First ceratopsians
    -First pachycephalosaurids
    -First flowering plants
    -Extinction of dinosaurs 65 MYA at the end of the Cretaceous
    -More break-up of Pangea
    -Diverse life and many dinosaurs
    -Mammals still survived after the extinction
    -Large scale geographic isolation
    -Asteroid caused estinction
  • Cenozoic 65 MYA - Present Day

    Cenozoic 65 MYA - Present Day
    -Major evolution of mammals; Age of mammals
    -Largest land mammals of all time
    -First humans
    -Evolution of humans
    -Continents form to modern day shapes
  • Tertiary 65 MYA - 3 MYA

    Tertiary 65 MYA - 3 MYA
    -Continents shift into shapes and places similar to today's continents
    -India collided with the Eurasian plate
    -Major volcanic activity
    -Mammals replace dinosaurs as the dominant animals
  • Paleocene 65 MYA - 59 MYA

    Paleocene 65 MYA - 59 MYA
    -World is recovering from mass extinction
    -Subtropical climate
    -First epoch in Cenozoic Era
    -Mammals evolve and diversify
    -Large amounts of methane in the seafloor sediment
    -Ocean temperatures were high
    -Ice caps where absent
  • Eocene 59 MYA - 38 MYA

    Eocene 59 MYA - 38 MYA
    -Oldest known fossils of modern-known mammals
    -Highest mean annual temperatures of the entire Cenozoic Era
    -High precipitation
    -Ice-free world
    -Important time of plate boundary rearrangement
    -Global cooling event at the end of the Eocene
    -Open savannah-like vegetation
    -Reduction in forests
    -First horses
  • Oligocene 38 MYA - 26 MYA

    Oligocene 38 MYA - 26 MYA
    -First elephants
    -Appearance of many grasses
    -Huge diversity of mammals
    -Decline in total number of marine species
    -First primates
    -"Grand Coupure" happened, where there was a huge diversification and evolution of mammals
    -Expansion of grasslands and praires
    -First huge mammals
  • Miocene 26 MYA - 12 MYA

    Miocene 26 MYA - 12 MYA
    -Hoofed mammals underwent rapid evolution
    -Warmer global climate than Oligocene or Pliocene
    -Expansion of grasslands
    -Many morphological changes in mammals
    -Rise of the Andes mountains in South America
    -First kelp forests underwater
    -First sea otters
    -Antarctica becomes isolated
  • Pliocene 12 MYA - 3 MYA

    Pliocene 12 MYA - 3 MYA
    -Expansion of grassland and savannah
    -Rapid diversification of grazing mammals
    -Period of global cooling after the Miocene before it
    -Change in vegetation
    -Accumulation of ice at the poles
    -Shifting in tectonic plates created similar continents to today's
    -Formation of the Himalayas
    -Global climate got cooler and more arid
    -Many mountain ranges in Europe were built up
    -First human-like apes in late Pliocene
    -Medditerranean Sea dried up completely
  • Quaternary 3 MYA - Present Day

    Quaternary 3 MYA - Present Day
    -Ice age
    -First humans
    -Continues into present day
    -Continents reach present day outlines
    -Sea levels rise
    -Ice sheets cover much of the world
    -Age of Humans
    -Major human evolution
    -Major extinction of large mammals
  • Pleistocene 3 MYA - 10,000 YA

    Pleistocene 3 MYA - 10,000 YA
    -Major ice age
    -Great Lakes form
    -Many modern mammals live
    -Evolution of humans, Homo Sapiens
    -Pleistocene fossils can be dated very precisely
    -Extinction in Pleistocene wiped out many mammals;cause unknown
    -Most recent ice age
  • Holocene 10,000 YA - Present Day

    Holocene 10,000 YA - Present Day
    -Humans start first civilizations
    -First technology
    -The epoch that we're currently in
    -Earth warms and ice age ends
    -Sea levels rose
    -Animals and plants have not evolved much since Pleistocene