出典:Wiktionary
出典:『Wiktionary』 (2025/12/23 04:26 UTC 版)
From Greek sideros.
Siderian (comparative more Siderian, superlative most Siderian)
出典:Wikipedia
出典:『Wikipedia』 (2010/11/14 14:43 UTC 版)
The Siderian (pronounced /saɪˈdɪəriən/, Greek: sideros, meaning "iron") is the first geologic period in the Paleoproterozoic Era and lasted from 2500 Mya to 2300 Mya (million years ago). Instead of being based on stratigraphy, these dates are defined chronometrically.