Siderian

The Siderian Period (pronunciation: /saɪˈdɪəriən/; Greek: sideros, meaning "iron") is the first geologic period in the Paleoproterozoic Era and lasted from 2500 Ma to 2300 Ma (million years ago). Instead of being based on stratigraphy, these dates are defined chronometrically.

Siderian

The Siderian Period (pronunciation: /saɪˈdɪəriən/; Greek: sideros, meaning "iron") is the first geologic period in the Paleoproterozoic Era and lasted from 2500 Ma to 2300 Ma (million years ago). Instead of being based on stratigraphy, these dates are defined chronometrically.