1. A period of the Archaean, dated at about 3850–3800 Ma ago (Harland et al., 1989). The name is no longer used.
2. Two epochs in the lunar timescale, the Lower Imbrian (3850–3800 Ma ago) and the Upper Imbrian (3800–3200 Ma ago).
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。