EARTH SCIENCE

Viewpoint: Yes, the timing of the rise in Earth's atmospheric oxygen was triggered not by biological processes but by geological processes such as volcanic eruption, which transported elements (among them oxygen) from Earth's interior to its atmosphere.

Viewpoint: No, the theories based on geological principles accounting for the timing of the rise in Earth's atmospheric oxygen have insufficient data to supplant biological processes as the cause.

As most people know, oxygen is essential to most forms of life, with the exclusion of anaerobic or non-oxygen-dependent bacteria. But when, and from where, did this life-giving oxygen arise during the course of Earth's history? The first question, regarding the point...