Tonian (from Greek τόνος (tónos), meaning "stretch") is the
first geologic period of the
Neoproterozoic Era. It lasted from 1000
Mya to 720 Mya (million years ago). Instead of being based on
stratigraphy, these dates are defined by the ICS based on radiometric
Tonian is preceded by the
Stenian Period of the
Mesoproterozoic era and followed by the Cryogenian.
Boring Billion Riphean (stage)
Tonian Period". GeoWhen Database. Archived from the original on May
12, 2006. Retrieved January 5, 2006.
James G. Ogg (2004). "Status on Divisions of the International
v t e
Siderian Rhyacian Orosirian Statherian
Calymmian Ectasian Stenian
Tonian Cryogenian Ediacaran
This geochronology article is a stub. You can help by expanding it.