Scientists researching conditions on primordial Earth have been afforded a great deal of insight thanks to tiny bubbles that formed inside lava rock 2.7 billion years ago.
Researcher say that they have been able to analyze gas bubbles from inside ancient basalt rock in order to work out how things have changed on Earth since that time. The gas bubbles were found inside ancient lava flows in western Australia, and revealed that Earth had a thinner atmosphere and air pressure half of what we are used to today, writes Will Dunham for Business Insider.
Lava flows reveal fascinating information on primordial Earth
Previously held wisdom had us believe that Earth had a thicker notion in those days in order to make up for a fainter sun. Sunlight was around 15% dimmer back then and it continues to get brighter as part of the natural evolution of our star.
Earth is known to have formed around 4.5 billion years ago, and conditions were still very different around 2.7 billion years ago. Sunlight was dimmer, oxygen levels were low, tides were stronger as the moon was closer to the Earth, our planet spun more quickly making for shorter days and the only form of life were single-cell microbes, said study leader Sanjoy Som, CEO of Seattle-based Blue Marble Space, a nonprofit organization focusing on space science research, education and public outreach.
Som said that the findings show how “a planetary environment completely different than modern Earth can sustain life on its surface.” He worked on the study at the University of Washington before moving to NASA’s Ames Research Center in California.
“Life doesn’t need conditions like modern Earth to survive and thrive. This is important in our quest for habitable environments in extra-solar planets,” Som added.
Greenhouse gases abundant in ancient atmosphere
Analysis of size and distribution of the gas bubbles was undertaken using sophisticated scanning technology. The ancient lava rock had solidified at sea level along the Beasley River in western Australia.
The lava cools quickly from top to bottom, leaving bubbles trapped within the rock. Bubbles at the bottom are smaller than those at the top, with the size difference allowing scientists to work out the atmospheric pressure which pushed down on the lava as it cooled.
“It’s really bold, really ambitious, and fraught with difficulties,” says Dork Sahagian, a geologist at Lehigh University in Bethlehem, Pennsylvania, who was responsible for inventing the lava bubbling technique during the 1980s. “But you’ve got to try it. It’s as good a proxy of the pressure as you can hope to find.”
Scientists say greenhouse gases were prevalent
This latest research suggests that the atmosphere contained high levels of greenhouse gases at that point in Earth’s history.
“This study doesn’t yield direct knowledge about the air composition,” Som said. “Nonetheless, because most of the air pressure is nitrogen, and you needed greenhouse gases to compensate for a faint sun, methane – a powerful greenhouse gas – was a likely important constituent, as well as water vapor – another powerful greenhouse gas.”
The full findings of the study have been published in the journal Nature Geoscience. Scientists are now looking out for even older lava rock with gas bubbles trapped inside. They have hinted that older samples could be found in South Africa, but their exact location is a closely guarded secret for the moment.