British Ice Sheet dynamics inferred from North Atlantic ice-rafted debris records spanning the last 175 000 years

Sediment core MD04-2822 from the Rockall Trough, northeast Atlantic, provides lithological evidence for the expansion of the British Ice Sheet (BIS) onto the Hebridean margin during both the penultimate (Marine Isotope Stage (MIS) 6/Wolstonian/Saalian) and last glaciation (Devensian/Weichselian). A composite chronology is constructed using: (i) the benthic foraminiferal oxygen isotope record, matched to an orbitally tuned stacked record of global ice volume (SPECMAP); (ii) the synchronisation of the planktonic foraminiferal (Neogloboquadrina pachyderma (sinistral)) and ITRAX XRF Ca records to the Greenland ice core (NGRIP) back to ca. 123 ka; and (iii) the synchronisation of the same N. pachyderma (sinistral)) and ITRAX XRF Ca records to the atmospheric methane record of the Antarctic ice core (EPICA Dome C) beyond 123 ka. The first offshore evidence for the expansion of the last BIS within MIS 4 is presented, suggesting extensive glaciation of northwestern Britain during the Devensian/Weichselian as early as 70 ka. The proximity of this long sediment core to the glaciated margin of northwestern Scotland makes it ideal to capture the ice-rafted debris (IRD) signal of the BIS for the last 175 ka, via a continuous flux record of IRD. British Geological Survey (C) NERC 2009. All rights reserved.