Access

News and Views

Nature 423, 592-593 (5 June 2003) |

Biogeochemistry: Ancient oceans and oxygen

Matthew T. Hurtgen

Top

The ocean chemistry of 1.5 billion years ago, inferred from rocks of that age, supports the view that marine conditions then were very different from those that pertained at earlier and later times.

Discovering how oxygen levels in Earth's atmosphere and oceans have varied over time is a goal of compelling interest — not least because of the oxygen-dependence of so many life-forms, including ourselves. But how do you estimate an oxygenation state that existed back in deep time?