Researchers have discovered an "unexpected" accumulation of the radioactive isotope beryllium-10, deep underneath the surface of the Pacific Ocean. As detailed in a paper published in the journal Nature Communications,

Could this beryllium-10 anomaly in the Pacific mark the beginning of the modern global ocean circulation? If ocean currents were responsible, beryllium-10 would be distributed unevenly on Earth with some samples even showing a lack of beryllium-10. New samples from all major oceans and both hemispheres would allow us to answer this question.

Earth must have experienced something exceptional 10 million years ago. Our study of rock samples from the floor of the Pacific Ocean has found a strange increase in the radioactive isotope beryllium

A strange radioactive 'blip' has been detected deep beneath the Pacific Ocean. Analyzing several thin layers of seafloor crust, scientists in Germany have identified a sudden surge in the radioactive isotope Beryllium-10 sometime between 9–12 million years ago.