Proterozoic geochronology

The Ediacaran ( ) is a geological period of the Neoproterozoic Era that spans 96 million years from the end of the Cryogenian Period at 635 Mya to the beginning of the Cambrian Period at 538.8 Mya. It is the last period of the Proterozoic Eon as well as the last of the so-called "Precambrian supereon", before the beginning of the subsequent Cambrian Period marks the start of the Phanerozoic Eon, where recognizable fossil evidence of life becomes common.

The Cryogenian (from , meaning "cold" and , romanized: , meaning "birth") is a geologic period that lasted from . It is the second of the three periods of the Neoproterozoic era, preceded by the Tonian and followed by the Ediacaran.

The Tonian (from , meaning "stretch") is the first geologic period of the Neoproterozoic Era. It lasted from to Mya (million years ago). Instead of being based on stratigraphy, these dates are defined by the ICS based on radiometric chronometry. The Tonian is preceded by the Stenian Period of the Mesoproterozoic Era and followed by the Cryogenian.

The Stenian Period ( , from , meaning "narrow") is the final geologic period in the Mesoproterozoic Era and lasted from Mya to Mya (million years ago). Instead of being based on stratigraphy, these dates are defined chronometrically due to the scarcity of Precambrian fossils and lack of reliable zonation. It is preceded by the Ectasian Period and followed by the Neoproterozoic era and the Tonian period.

The Siderian () is the first geologic period in the Paleoproterozoic Era and Proterozoic Eon. It lasted from  to  million years ago (Ma), spanning 200 million years, and is followed by the Rhyacian Period. Instead of being based on stratigraphy, these dates are defined chronometrically.

The Rhyacian () is the second geologic period in the Paleoproterozoic Era. It spans 250 million years and lasted from to million years ago (Ma), following the Siderian Period and preceding the Orosirian Period. These dates are defined chronometrically rather than stratigraphically.

The Statherian (; , meaning "stable, firm") is the fourth and final geologic period in the Paleoproterozoic Era, lasting from to million years ago (Ma) and spanning 200 million years. It follows the Orosirian Period and precedes the Calymmian Period, with the latter belonging to the Mesoproterozoic Era. Instead of being based on stratigraphy, these dates are defined chronometrically.

The Ectasian Period (from , meaning "extension") is the second geologic period in the Mesoproterozoic Era and lasted from Mya to Mya (million years ago). Instead of being based on stratigraphy, these dates are defined chronometrically.

The Calymmian (from , meaning 'cover') is the first geologic period in the Mesoproterozoic Era, lasting from to million years ago (Ma) and spanning 200 million years. It follows the Statherian Period from the Paleoproterozoic Era, and precedes the Ectasian Period. Instead of being based on stratigraphy, these dates are defined chronometrically.

The Orosirian (; , meaning "mountain range") is the third geologic period in the Paleoproterozoic Era. It spans 250 million years and lasted from to million years ago (Ma), following the Rhyacian Period and preceding the Statherian Period. Instead of being based on stratigraphy, these dates are defined chronometrically.