Giant bolide hit South Africa 2.5 billion years ago

Some of the oldest scraps of continental crust on Earth cling to the southern tip of Africa and the western edge of Australia. In both places, geologists have found rock layers rich in tiny particles called spherules. Scientists think spherules form when meteorites strike the planet, vaporizing surface rocks that then condense into small droplets, blanketing the surrounding landscape. Now, research published in Geology confirms the extraterrestrial origin of a 2.5-billion-year-old layer of spherules in South Africa, which scientists say was produced by a bolide at least as large as the one that doomed the dinosaurs.
 

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Julia Rosen

Rosen holds a doctorate in geology and is a freelance science writer based in Portland, Ore. She has served as both an intern and an interim staff writer for EARTH, has also written for the Los Angeles Times and AGU’s Eos, and occasionally hosts 60-Second Science podcasts for Scientific American. Find more of her work at www.julia-rosen.com.

Saturday, June 6, 2015 - 06:00