Indication for Supernova Produced ${}^{60}\mathrm{Fe}$ Activity on Earth

In a deep ocean ferromanganese crust an excess of ${}^{60}\mathrm{Fe}$ radioactivity was measured by means of high sensitivity accelerator mass spectrometry. The enhanced concentrations measured in the first two of three layers (corresponding to a time span of 0–2.8 Myr and 3.7–5.9 Myr, respectively) suggest the deposition of supernova produced ${}^{60}\mathrm{Fe}$ on earth. There is even a weak indication that the flux into the crust was higher about 5 Myr ago.