The base of the Norian stage is set at ~228 Ma on the new chronstratigraphy chart of the International Commission on Stratigraphy. Still needs further support and eventially a golden spike, but this is the first time the ICS has used the long Norian hypothesis on its published chart.
You can download the latest timescale from here:
http://www.stratigraphy.org/ics%20chart/ChronostratChart2012.pdf
Blog update
3 hours ago in The Phytophactor
Clicking on the above link, or first copying then pasting, brings a site in Japanese (?) which translated into English states that there is an error. Sincerely, Howard McPherson
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