Study reveals that early Earth may have been a waterworld without continents

"Waterworld" may not be just a Hollywood movie, at least not according to the results of a study published on March 2 in Nature Geoscience.

University of Colorado Boulder associate professor Boswell Wing, who works in the Department of Geological Sciences, co-authored the paper with lead researcher Benjamin Johnson, who was working in a postdoctoral position in Wing’s lab when he conducted this research. Johnson is now an associate professor at Iowa State University in Ames.

The study suggests that the early Earth’s surface was covered by a global ocean billions of years ago.  

Wing and Johnson focused on a geologic site in Northwestern Australia’s Outback, called the Panorama district, where a 3.2-billion-year-old chunk of ocean crust has been turned on its side.  

That chunk of ocean crust allowed Wing and Johnson to learn about the chemistry of ocean water as it existed billions of years ago.

“There are no samples of really ancient ocean water lying around, but we do have rocks that interacted with that seawater and remembered that interaction,” Johnson said. 

They analyzed data from more than 100 rock samples across the Panorama district, where you can actually walk on the hard outer shell of the planet – or what used to be that shell, from the base to hydrothermal vents where water bubbled up. 

They were looking for oxygen-18 and oxygen-16, isotopes they thought might be trapped in the stone, and found more of the heavier isotope, oxygen-18, in the rock.

They theorize that there wasn’t a lot of soil-rich land to soak up the isotopes – they’re not saying there weren’t any, just not an abundance of those spots. 

Johnson and Wing plan to examine younger rock formations around the world to see whether they can determine when land masses may have arisen from the global ocean.