නීරස බිලියනය – ඉතිහාසයේ මුල් යුගයේ අදට වසර බිලියන 1.8 පෙර සිට වසර බිලියන 0.8 දක්වා වූ කාලය, characterized by tectonic stability, climatic stasis, and a slow biological evolution with very low oxygen levels and no evidence of glaciation
Geological history of oxygen – Timeline of the development of free oxygen in the Earth's oceans and atmosphere
Lyons, Timothy W.; Reinhard, Christopher T.; Planavsky, Noah J. (February 2014). "The rise of oxygen in Earth's early ocean and atmosphere". Nature. 506 (7488): 307–315. Bibcode:2014Natur.506..307L. doi:10.1038/nature13068. PMID24553238. S2CID4443958.