A stage (447.5–446.5 Ma ago) of the Ordovician in the Ashgill, underlain by the Pusgillian and overlain by the Rawtheyan.
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。