The appearance of oxygen in the Earth’s atmosphere probably did not occur as a single event, according to an international team of researchers who investigated rock cores.
Researchers drilled a series of shallow, two-inch diameter cores and, by overlapping them, created a record representing stone deposited during the Proterozoic Eon—2,500 million to 542 million years ago.
“We’ve always thought that oxygen came into the atmosphere really quickly during an event,” said Lee R. Kump, professor of geosciences at Penn State University. “We are no longer looking for an event. Now we are looking for when and why oxygen became a stable part of the Earth’s atmosphere.”Read more at Futurity