At the bottom of the Pacific Ocean, beneath kilometers of water, an unassuming black rock has been growing for millions of years. It grows only a few millimeters every million years, yet in doing so, it records cosmic history. Researchers from the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) have now deciphered this history.
Together with colleagues from Sydney and Canberra, they have examined a so-called ferromanganese crust from the deep sea. These mineral deposits form at depths ranging from several hundred to several thousand meters. They grow millimeter by millimeter over millions of years, absorbing and storing substances from their surroundings. This includes tiny amounts of radioactive isotopes.
Isotopes are variants of a chemical element that differ in mass. For scientists, these atoms are like a diary of cosmic events.
