Darriwilian

The Darriwilium is in Earth's history, the second stage of the chronostratigraphic Mittelordovium series of the Ordovician. The level corresponds approximately to the geochronological period of about 467.3 to about 458.4 million years. The Darriwilium following the Dapingium and is in turn replaced by Sandbium.

Naming and history

The stage is named after the place Darriwil in the County of Grant ( Victoria, Australia). Name and level have been proposed in 1899 by Thomas Sergeant Hall ( 1858-1915 ). The Darriwilium corresponds to the highest part of the former Arenigium series ( or stage ) and the lower part of the former Llanvirnium series ( or level).

Definition and GSSP

The lower limit of Darriwilium was defined by the first appearance of the graptolite - type Undulograptus austrodentatus, the upper limit by the first appearance of the graptolite - type Nemagraptus gracilis. As a global reference profile ( GSSP = Global Stratotype Section and Point) of Darriwilium but a profile on Huangnitang, county Changshan, Zhejiang Province in southeastern China has been set.

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