Earth's Thin Early Atmosphere Revealed in Bubbles
Source: Agence France-Presse
Earth's Thin Early Atmosphere Revealed in Bubbles
MAY 10, 2016 02:22 PM ET // BY AFP
Air bubbles trapped in 2.7 billion-year-old lava flows in the Pilbara suggest the Earth’s atmosphere weighed less than half that of today and was far thinner than previously thought.
The discovery has forced a rethink of how the Earth managed to stay relatively ice-free during that period, despite the sun being much cooler than it is today.
In a study published today in Nature Geoscience, researchers analysed the relative sizes of air bubbles across ancient lava flows along the Beasley River in Western Australia’s Pilbara region.
The lava flows — discovered by Australian researcher Dr Tim Blake, then at the University of Western Australia — bear distinctive features such as lava “toes” with cracked, glassy rinds, which suggested the molten rock once flowed over a beach.
Astrobiologist Professor David Catling, one of the study’s authors from the University of Washington, said the Sun was roughly 20 percent less luminous 2.7 billion years ago, so if Earth had an atmosphere similar to today it would have been covered in ice. Yet similar conditions as today prevailed.
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Read more: http://news.discovery.com/earth/earths-thin-early-atmosphere-revealed-in-bubbles-160510.htm
Related: Earth's air pressure 2.7 billion years ago constrained to less than half of modern levels (Nature Geoscience)
