This graphic shows historical variations of Mercury (Hg) deposition before and after the Latest Permian Extinction event as recorded in a sedimentary section in the High Arctic, Canada.  The vertical axis demonstrates the depth of the sedimentary section relative to the extinction boundary while the horizontal looks at the amount of mercury accumulation (concentration in the rock) as measured in milligram per kilogram. Credit: Hamed Sanei, Steve Grasby and Benoit Beauchamp. (Sanei et al., 2012, Geology)