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Earth and Space Sciences · Glossary

What is Hadean, Archean, Proterozoic?

Also known as: Hadean · Archean · Proterozoic

Definition 18.1 University Earth and Space Sciences — Year 2 · Chapter 18 — The Precambrian Earth

The time before the Phanerozoic is divided into three eons. The Hadean runs from the formation of the Earth, 4567 Ma4567\,\mathrm{Ma} ago, to 4031±3 Ma4031 \pm 3\,\mathrm{Ma}; the Archean from 40314031 to 2500 Ma2500\,\mathrm{Ma}; the Proterozoic from 2500 to 538.8 Ma538.8\,\mathrm{Ma}, the base of the Cambrian. Together they are informally called the Precambrian.

The Precambrian on one line. The eons and, in lighter tints, their eras (Eo-, Paleo-, Meso- and Neoarchean; Paleo-, Meso- and Neoproterozoic) are those of the International Chronostratigraphic Chart; the events are placed at the ages quoted in the text. The “last common komatiites” are the aluminium-undepleted ones; younger, rarer kinds exist.
The Precambrian on one line. The eons and, in lighter tints, their eras (Eo-, Paleo-, Meso- and Neoarchean; Paleo-, Meso- and Neoproterozoic) are those of the International Chronostratigraphic Chart; the events are placed at the ages quoted in the text. The “last common komatiites” are the aluminium-undepleted ones; younger, rarer kinds exist.
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