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    Tables – Geological eras of earth

    Geological EraApproximate TimescaleShort Description
    Hadean4.6 to 4.0 billion years agoNamed after Hades, the ancient Greek god of the underworld. This era is associated with the formation of the Earth and the establishment of its early oceans.
    Archean4.0 to 2.5 billion years agoThe Earth’s crust had begun to solidify, life first appeared, and the Earth’s atmosphere and oceans formed.
    Proterozoic2.5 billion to 541 million years agoNamed for the Greek words for “earlier life”. This era was characterized by the buildup of oxygen in the atmosphere and the development of simple multicellular organisms.
    Paleozoic541 to 252 million years agoDerived from the Greek words for “ancient life”, the Paleozoic era was when life as we know it took off with an explosion of diversity.
    Mesozoic252 to 66 million years agoKnown as the age of dinosaurs, it was during the Mesozoic era that reptiles and mammals began to evolve, and the supercontinent Pangea began to drift apart.
    Cenozoic66 million years ago to the presentKnown as the age of mammals, this era saw the rise of mammals and flowering plants, the formation of the Himalayas and Alps, and the evolution of humans.