Interactions between secondary cosmic rays and nuclei in natural minerals can leave tracks in the
lattice due to nuclear recoils. These defects can be preserved up to the Gyr timescale, making these
so-called “Paleo-detectors” useful “time machines” for the study of the history of astrophysical
messengers such as cosmic rays, neutrinos or even dark matter. These "Paleo-detectors" feature
huge accumulated exposure times even for small masses of material, making them long-term flux
integrators of all radiation along the evolution of our planet. We present the case study of the
Messinian salinity crisis, a period of draining of the Mediterranean Sea which is interestingly
coincident with the estimated age of the Fermi Bubbles, around 5.5 Myr ago, when our Galaxy
might have been active. Greatly increased cosmic ray acceleration near the Galactic Center could
have left traces in the evaporites, mainly Halite, created with the evaporation of the sea and exposed
directly to secondary cosmic rays. These mineral structures were then covered during the sudden
reflooding of the Mediterranean basin 5.3 Myr ago; the cosmic ray flux information remained
frozen due to the shielding of the massive body of water, possibly retaining information on the
flux of particles at ground in that epoch.