Billions of years before a smaller asteroid slammed Earth, triggering a global blackout that would wipe out the dinosaurs, a rock four times the size of Mount Everest made an even bigger splash. Researchers have long known about the impact, dubbed S2, which occurred 3.26 billion years ago, based on the discovery of tiny glass beads called spherules, which formed from vaporized material from the impact. But new research presented at the American Geophysical Union’s fall meeting in San Francisco is revealing more about its significance. As the Washington Post reports, three groups of scientists working independently conclude the impact made the planet more compatible to life. But first, it was a hellscape.
The rock that struck the planet was at least 23 miles wide, or nearly four times the size of the asteroid that formed the Chicxulub crater some 66 million years ago, EarthSky reported in 2014. It probably landed in the ocean, as computer models indicate there would’ve been little landmass at the time. “The collision was so violent it boiled off the top layer of that ocean and, near the impact site, created a tsunami as high as a New York skyscraper,” per the Post. “Molten rock rained from the sky. The atmosphere was choked with ash and dust.” But “these negative effects probably didn’t last very long,” Harvard geologist Nadja Drabon, who presented at the AGU meeting, tells the Post. And in the aftermath came transient benefits for the simple organisms that formed early life.
In mixing up the water column, the tsunami would’ve added iron, an essential element for almost all living organisms, to shallow seas. “In addition, the post-impact hothouse environment may have led to increased erosion and weathering, injecting nutrients like phosphorus into the oceans” reads the caption of a video in which Drabon describes her research in detail. In addition to adding mass to the planet, the impact and others like it—there were 16 major ones between 3.5 billion and 2.4 billion years ago, per the Post—could have deposited “key elements or molecules that were missing in the near-surface that perhaps could have been important for early life,” adds Simone Marchi, a planetary scientist at the Southwest Research Institute, who also presented at the AGU meeting. (Read more geology stories.)
