Siderian

The Siderian (pron.: /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.

Abundance of banded iron formations (BIFs) peaked early this period. BIFs were formed as anaerobic algae produced waste oxygen that combined with iron, forming magnetite (Fe₃O₄, an iron oxide). This process cleared iron from the oceans, presumably turning greenish seas clear. Eventually, without an oxygen sink in the oceans, the process created the oxygen-rich atmosphere of today. This event is known as the oxygen catastrophe, which according to some geologists triggered the Huronian glaciation. The Huronian glaciation took place in the Siderian between 2400 Mya and 2300 Mya.

References

• "Siderian Period". GeoWhen Database. Retrieved January 5, 2006. 

Notes

Preceded by Archean Eon	2.5 Ga - Proterozoic Eon - 542 Ma										Followed by Phanerozoic Eon
	2.5 Ga - Paleoproterozoic Era -1.6 Ga				1.6 Ga - Mesoproterozoic Era -1.0 Ga			1.0 Ga - Neoproterozoic Era -542 Ma
	Siderian	Rhyacian	Orosirian	Statherian	Calymmian	Ectasian	Stenian	Tonian	Cryogenian	Ediacaran