If you’re looking to really learn about the history of our planet, look to geology. Ancient rocks can provide a time capsule of the conditions in which they formed. But even the geologic record has its limits—rocks and minerals get weathered, buried, heated, melted, and recycled over time—so geologists need to search out rare super-old geologic holdouts to tell about the earliest times.
Writing in the journal Nature in July, researchers described what they can learn about the chemical history of Earth’s mantle, the geologic layer beneath the planet’s crust, from studying 2.5 billion-year-old rocks collected at spreading ocean ridges. They found that these unusual mantle rocks didn’t necessarily have to have been formed in a world with less available oxygen, but could have been produced just by the mantle layer being hotter long ago.
Dr. Elizabeth Cottrell, chair of the Department of Mineral Sciences at the Smithsonian’s National Museum of Natural History, joins Ira to talk about the research and why a collection of old rocks is an important part of international scientific infrastructure.
Further Reading
- Read about Dr. Cottrell’s field work on volcanoes and her quest to understand the origins of Earth’s surface via Smithsonian.
Segment Guests
Elizabeth Cottrell
Dr. Elizabeth Cottrell is chair of the Department of Mineral Sciences at the Smithsonian’s National Museum of Natural History in Washington, DC.
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@cbquistAs Science Friday’s director and senior producer, Charles Bergquist channels the chaos of a live production studio into something sounding like a radio program. Favorite topics include planetary sciences, chemistry, materials, and shiny things with blinking lights.
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@iraflatowIra Flatow is the host and executive producer of Science Friday. His green thumb has revived many an office plant at death’s door.