A stage (453–447.5 Ma ago) of the Late Ordovician in the Middle Cincinnatian series of N. America, preceded by the Actonian and followed by the Onnian.
科学参考收录了60776条科技类词条，基本涵盖了常见科技类参考文献及英语词汇的翻译，是科学学习和研究的有利工具。