10Be evidence for the Matuyama-Brunhes geomagnetic reversal in the EPICA Dome C ice core

An ice core drilled at Dome C, Antarctica, is the oldest ice core so far retrieved(1). On the basis of ice flow modelling and a comparison between the deuterium signal in the ice with climate records from marine sediment cores, the ice at a depth of 3,190 m in the Dome C core is believed to have been deposited around 800,000 years ago 2, offering a rare opportunity to study climatic and environmental conditions over this time period. However, an independent determination of this age is important because the deuterium profile below a depth of 3,190 m depth does not show the expected correlation with the marine record(2). Here we present evidence for enhanced 10 Be deposition in the ice at 3,160 - 3,170 m, which we interpret as a result of the low dipole field strength during the Matuyama - Brunhes geomagnetic reversal, which occurred about 780,000 years ago. If correct, this provides a crucial tie point between ice cores, marine cores and a radiometric timescale.