The Proterozoic is the youngest of the two great divisions of the Precambrian and ranges from 2,500 to 542 Ma.
The Proterozoic Eon begins at 2.5 Ga, which approximately marks the time when oxygen from cyanobacteria began to dramatically change the composition of the Earth’s atmosphere and oceans and when complex one-celled life (eukaryotes) evolved from simple cells (prokaryotes). The Proterozoic is subdivided into ten periods, generally of 200-Myr duration, grouped into three eras. The poetic names for these periods (see International Stratigraphic Chart: www.stratigraphy.org) are derived from the larger-scale tectonic or sedimentary features that occurred within each period. For example, the Siderian Period (2.5–2.3 Ga) is named from the banded iron deposits (sideros = iron) that peaked within that interval. The lack of a diverse and well-preserved fossil record, the sparse volume of supracrustal rocks, a variable degree of metamorphism and tectonic disturbance,...
KeywordsBanded iron formation Eukaryotes Geological timescale Great oxygenation event Precambrian
References and Further Reading
- Ogg JG, Ogg G, Felix M (2008) Gradstein. The concise geologic time scale. Cambridge University Press, Cambridge, p 177Google Scholar