A stage (445.6–443.7 Ma ago) of the Late Ordovician epoch in the Upper Ashgill, underlain by the Rawtheyan and overlain by the Rhuddanian (Silurian).
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。