Tonian
From Freepedia
The Tonian (from Greek tonas, "stretch") is the first geologic period in the Neoproterozoic Era and lasted from 1000 Ma to 850 Ma (million years ago). Instead of being based on stratigraphy, these dates are defined chronometrically.
Events leading to breakup of supercontinent Rodinia started in this period.
The first radiation of acritarchs occurred during the Tonian.
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| Proterozoic eon | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| Paleoproterozoic era | Mesoproterozoic era | Neoproterozoic era | |||||||
| Siderian | Rhyacian | Orosirian | Statherian | Calymmian | Ectasian | Stenian | Tonian | Cryogenian | Ediacaran |
