Some of the oldest air ever studied by scientists was trapped inside rock over 800 million years ago. Cracking the rock open and allowing the air to escape, the team who found it got a pretty astonishing surprise about the ancient atmosphere of Earth. The rest of this article is behind a paywall. Please sign in or subscribe to access the full content.

When studying the Earth's atmosphere in the ancient past, scientists have had to rely on indirect evidence to estimate element abundancies. But that's not altogether ideal, involving complex analyses and estimates. Another method is to look at air trapped in the Antarctic ice .

"Like a prehistoric fly trapped in amber during dinosaurs' days, airborne relics of Earth's earlier climate –including dust, air bubbles, sea salts, volcanic ash,

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