Floian

The Floian is the second stage of the Ordovician Period. It succeeds the Tremadocian with which it forms the Lower Ordovician series. It precedes the Dapingian Stage of the Middle Ordovician. The Floian extended from 477.1 to 471.3 million years ago. The lower boundary is defined as the first appearance of the graptolite species Tetragraptus approximatus.

← Geological time scale