Widespread Ancient Ocean "Dead Zones" Challenged Early Life

Widespread Ancient Ocean "Dead Zones" Challenged Early Life
Wed, 05 Jan 2011 12:48:00 -0600

The oceans became oxygen-rich as they are today about 600 million years ago, during Earth's Late Ediacaran Period. Before that, most scientists believed until recently, the ancient oceans were relatively oxygen-poor for the preceding four billion years.

Now biogeochemists at the University of California-Riverside (UCR) have found evidence that the oceans went back to being "anoxic," or oxygen-poor, around 499 million years ago, soon after the first appearance of animals on ...

More at http://www.nsf.gov/news/news_summ.jsp?cntn_id=118330&WT.mc_id=USNSF_51&WT.mc_ev=click

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