Geological eons, periods and epochs

The timeline below runs from the formation of our planet Earth 4.6 billion years ago (4.6 Bya), to 2 million years ago (2 Mya), at the first appearance of Homo erectus. Its log-scale equally spaces successive intervals in time halfway to the present from the last; for example, 1 Bya lies midway between 2 Bya and 500 Mya. This multiplicative scaling allows the same timeline to visualise earlier periods and manyfold shorter recent periods. For example, the Proterozoic Eon lasted almost 2 billion years, encompassing the earliest multicellular life, the arrival of Eukaryotes and amongst them the Metazoa (animals) including the first bilaterians, before the nearly 4× shorter Phanerozoic Eon, encompassing the last 540 million years from the Cambrian explosion of animal diversity through to the present. White bars encompass major ice ages; pink arrows point to mass extinction events. The epochs of our current Quaternary Period are plotted on a separate archaeological timeline (here).

C.P. Doncaster, Timeline of the Human Condition, star index