1. An age in the Early Devonian Epoch, preceded by the Gedinnian, followed by the Emsian, and dated at 401–394Ma.
2. The name of the corresponding European stage, which is roughly contemporaneous with the Merionsian (Australia), and the upper Helderbergian, Deerparkian, and lower Onesquethawian (N. America).
"Siegenian." A Dictionary of Earth Sciences. . Encyclopedia.com. (November 16, 2018). https://www.encyclopedia.com/science/dictionaries-thesauruses-pictures-and-press-releases/siegenian
"Siegenian." A Dictionary of Earth Sciences. . Retrieved November 16, 2018 from Encyclopedia.com: https://www.encyclopedia.com/science/dictionaries-thesauruses-pictures-and-press-releases/siegenian