15 BYA - 1 BYA


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  • Biology: Self-replicating RNA (4.15 BYA)
    Single-celled life - oldest robable microfossils (3.8 BYA)
    Oxygen producing bacteria and microfossils (3.6 BYA)
    Prokaryotic organisms and photosynthesis (3.5 BYA)
    First stromatolites - colonial bacteria (3.2 BYA)
    Photosynthesis builds earth's oxygen and prokaryotes form (2.8 BYA)
    Mitochondria capable of aerobic respiration (2.3 BYA)
    Bacteria and Archaea abundant 91.8 BYA)
    First protists with nuclei (1.8 BYA)
    First eukaryotes form - Green algaes colonize seas (1.5 BYA)
    Spores and gametes present - indicating sexual reproduction (1.2 BYA)
    Trace fossils of multicellular eukaryotes - dinoflagellates (1 BYA)
  • Chronology: Start of Archaeozoic (Archean) era as crust hardens 95 BYA)
    Start of the Hadeon eon and Cryptic era - earliest on earth (4.57 BYA)
    Basin Groups Era starts within Hadean Eon (4.15 BYA)
    Start of Nectarian Era (3.92 BYA)
    Early Inbrian Era within Hadean Eon (3.85 BYA)
    Eoarchaean Era (3.8 BYA)
    Paleoarchean Era (3.6 BYA)
    Start of Mesoarchean Era (3.2 BYA)
    Neoarchean Era of Archean Eon (2.8 BYA)
    End of Archean Eon - start of Proterozoic Eon and Siderian Period - Oxygen Catastrophy (2.5 BYA)
    Start of Huronian ice age (2.4 BYA)
    Start of Rhyacian Period (2.3 BYA)
    End of Huronian ice age (2.1 BYA)
    Start of Orosirian Period (2.05 BYA)
    Start of supercontinent Columbia (1.8 BYA)
    Start of the Statherian Period (1.8 BYA)
    End of Paleo-proterozoic and start of Mesoproterozoic era and Calymmian Period(1.6 BYA)
    Start of Archaeozoic Era and start of Proterozoic Era (1.5 BYA)
    Start of Ectasian Period of Meso-proterozoic Eras (1.4 BYA)
    Start of Stenian Period of Meso-proterozoic Era - Proterozoic Eon and Precambrian super-eon (1.2 BYA)Start of Tonian Period of neo-Proterozoic Era (1 BYA)
  • Climate: Formation of atmospheric ozone (1.6 BYA)
  • Earth: Formation of the earth (5 BYA)
    Earth's crust hardens (4.6 BYA)
    Impact causes the hydrogen and helium atmosphere to escape (4.45 BYA)
    Ozone layer starts to form due to solar decomposition of water (4.35 BYA)
    Earth re-melts due to radioactive and gravitational heating - layers form (4.3 BYA)
    Molten crust hardens and rainstorm of 60,000 years begins to fill the oceans (4.3 BYA)
    Oldest known rocks and life (4.15 BYA)
    Stop of bombardment of earth with planetessimals (4 BYA)
    Earth's atmosphere is CO2, water vapor, methane, and ammonia - Carbonate minerals start to form (3.85 BYA)
    Earth's crust solidifies - oldest rocks formed, Ocean waters condense, Earth's days are about 15 hours long (3.8 BYA)
    Oldest cratons (shields of lithosphere) form (3.6 BYA)
    Evidence of a magnetic field found (3 BYA)
    Atmosphere composed of 75% nitrogen and 15 CO2 (3 BYA)
    Stabilization of cratons (lithospheric plate centers)
    Possible mantle overturn 92.8 BYA)
    Dissolved oxygen found in oceans (2.5 BYA)
    Oxygen-soluble Uraninites stop forming and rusten iron deposits form in rocks - Great Oxidation Event (Catastrophy) (2.4 BYA)
    Glaciation and Bushveld Formation (2.3 BYA)
    Oxygen in the atmosphere becomes stronger, intense orogeny (mountain development) (2.08 BYA)
    Oxygen accumulates in atmosphere (2 BYA)
    Expansion of platform covers in sediment, last free iron used up - last banded iron formation and atmospheric oxygen increases - oxygen rises to 10% (1.6 BYA)
    Formation of metamorphic belts due to orogeny (1.2 BYA)
    Rodinia supercontinent forms (1.1 - 1 BYA)
  • Solar System: Estimated time of the Big Bang (15 BYA)
    Solar system fully formed but sun dimmer (4.57 BYA)
    Planetoid collides with Earth and moon forms (4.6 - 4.45 BYA)
    Lunar basins form on the moon (3.92 BYA)
    Heavy bombardment of inner solar system (3.85 BYA)
    Sun at 80% brightness (3 BYA)
    Solar luminosity estimated at 85% of current (2 BYA)


  • Meteor impact in Ontario, Canada (1.85 BYA)


  • Meteor impact in Vredefort South Africa (2.02 BYA)
    Oklo natural fission reactor in gabon goes into operation (2 BYA)